Oceans and Life
Oceans cover a large part of the Earth. They influence weather and climate, provide food and energy, support marine plants and animals, and connect countries through trade and transport.
Although we see only water at the surface, the ocean hides mountains, valleys, plains, deep trenches and natural resources. Ocean water is also constantly moving through waves, tides and currents. Understanding these features helps us use the oceans safely and protect their ecosystems.
1. The Big Questions
This chapter focuses on five important questions about the relationship between oceans, nature and human life.
1. Ocean Relief
How do underwater landforms influence marine life, navigation, resources and ocean exploration?
2. Ocean Water Movement
How do waves, tides and currents affect coastlines, weather, fishing and human activities?
3. Maritime Zones
How are the rights and responsibilities of coastal countries defined in different areas of the sea?
4. Sustainable Resources
How can the resources of the oceans be used without damaging marine ecosystems?
5. Early Warning Systems
How can technology and public awareness reduce the damage caused by cyclones and tsunamis?
Oceans in Indian culture: The ocean is traditionally called Samudra. It has an important place in Indian stories, rituals and cultural traditions, reflecting the close relationship between people and the sea.
2. Ocean Relief
The floor of an ocean is not flat. Like the land found on continents, it contains mountains, slopes, valleys, plains and deep depressions. The different physical features found beneath ocean water are called ocean relief or submarine relief.
These landforms are important because they influence the distribution of marine organisms, underwater resources, movement of ocean water and human activities such as fishing and ocean research.
2.1 Important Submarine Relief Features
Simplified ocean-floor profile. Horizontal distances and depths are not to scale.
| Relief Feature | Description | Importance |
|---|---|---|
| Continental Shelf | The shallow, submerged extension of a continent beneath the sea. | Rich fishing grounds and important sources of offshore oil and natural gas. |
| Continental Slope | The steep underwater slope beyond the continental shelf. | Marks the transition from shallow continental areas towards deeper ocean basins. |
| Continental Rise | A gently sloping region formed by sediments deposited near the foot of the continental slope. | Contains thick sediment deposits and connects the continental slope with the deep ocean floor. |
| Abyssal Plain | A very broad, deep and almost flat region of the ocean floor. | Supports deep-sea organisms and contains marine sediments. |
| Mid-Ocean Ridge | An extensive underwater mountain system associated with volcanic and tectonic activity. | Important for studying the formation and movement of Earth's crust. |
| Ocean Trench | An extremely deep, long and narrow depression in the ocean floor. | Important for understanding plate movements, earthquakes and deep-sea ecosystems. |
| Seamount | A mountain, usually of volcanic origin, that rises from the ocean floor but remains below sea level. | Provides habitats for many marine species. |
| Guyot | A flat-topped submarine mountain, generally formed when a former seamount is worn down and later submerged. | Provides evidence of past volcanic activity, erosion and changes in ocean-floor levels. |
| Submarine Canyon | A deep valley cut into the continental shelf or slope. | Channels sediments from shallow regions towards deeper ocean areas. |
2.2 Formation of Ocean Relief
Most major ocean-floor features are formed through movements of Earth's tectonic plates, volcanic activity, sediment deposition and erosion.
Other ocean-floor features, such as continental rises and broad sediment-covered plains, develop when particles carried by rivers and ocean currents accumulate over long periods.
Imp for Exams — Ocean Relief
- Continental shelf: Shallow and generally rich in fisheries and offshore resources.
- Continental slope: A steep descent towards deeper water.
- Abyssal plain: Broad, deep and relatively flat ocean floor.
- Mid-ocean ridge: Extensive underwater mountain system.
- Trench: One of the deepest features of the ocean floor.
- Guyot: Flat-topped submarine mountain.
2.3 Importance of Ocean Relief
Fishing
Shallow continental shelves receive light and nutrients, allowing plankton and fish populations to grow. These areas support major fishing industries.
Natural Resources
Oil, natural gas and other materials are extracted or researched in different regions of the ocean floor.
Navigation
Knowledge of underwater depths and obstacles helps ships select safe routes and avoid shallow areas and submerged mountains.
Underwater Research
Trenches, ridges and submarine mountains help scientists investigate marine organisms, earthquakes and Earth's geological history.
3. Movement of Ocean Water—Waves, Tides, and Currents
Ocean water is constantly moving. The three main types of ocean-water movement are waves, tides and ocean currents.
These movements have different causes, but all of them influence coastal landforms, marine ecosystems, climate, fishing and transportation.
Waves
Repeated rise and fall of the water surface, mainly due to wind.
Tides
Regular rise and fall of sea level due mainly to the gravitational influence of the Moon and Sun.
Currents
Continuous movement of ocean water in particular directions.
3.1 Waves
A wave is the alternating rise and fall of the ocean surface. Most ordinary ocean waves are produced when wind transfers energy to the surface of the water.
Waves carry energy across long distances. They are also important agents of coastal erosion and deposition.
Anatomy of Waves
The diagram shows the basic measurements and parts of a wave.
| Term | Meaning |
|---|---|
| Crest | The highest point of a wave. |
| Trough | The lowest point of a wave. |
| Wavelength | The horizontal distance between two successive crests or two successive troughs. |
| Wave Height | The vertical distance between a crest and the adjoining trough. |
| Wave Frequency | The number of wave crests passing a fixed point in one second. |
| Wave Period | The time between the arrival of two successive crests at a fixed point; equivalently, the time taken for a crest to travel one wavelength. |
Equations Related to Waves
Wave speed:
v = λ / T = f × λ
Where:
- v = wave speed (metres per second)
- λ = wavelength (metres)
- T = wave period (seconds)
- f = frequency (waves per second or hertz)
Relationship: f = 1 / T
These are supporting equations for understanding wave movement.
3.2 Landform Features Formed by Waves
Waves continuously change the shape of coastlines. They erode rocks, transport materials and deposit sediments.
For this reason, waves are sometimes described as coastal architects.
Formation of Erosional Landforms
When powerful waves repeatedly strike a rocky headland, pressure and abrasion gradually weaken the rock.
A simplified sequence showing how repeated wave erosion can change a rocky headland.
Stage 1 — Crack
Waves repeatedly strike weak points in coastal rocks. Hydraulic pressure opens and enlarges cracks.
Stage 2 — Sea Cave
Continued hydraulic action and abrasion enlarge the cracks into caves.
Stage 3 — Sea Arch
When wave erosion cuts through a headland, a natural arch may form.
Stage 4 — Sea Stack
The roof of the arch gradually weakens and collapses, leaving an isolated pillar of rock.
Stage 5 — Stump
Further erosion and weathering reduce the stack into a smaller rock formation called a stump.
Depositional Landforms
Waves do not only remove materials from the coast. They also deposit sand, pebbles and sediments when their energy decreases.
Beaches are common examples of coastal depositional landforms. They form through the accumulation of material moved by waves and coastal currents.
3.3 Dangerous Ocean Waves
During storms, very strong winds produce high waves that may damage coastal settlements, ports and fishing boats.
Another dangerous phenomenon is a tsunami — a series of powerful sea waves usually generated by sudden movement of the seafloor during an underwater earthquake.
Imp — Tsunami
Tsunamis can travel across entire ocean basins. In deep water, they may not appear very high, but as they reach shallow coastal regions, they can grow into destructive waves.
Run-up height is the maximum vertical height reached by tsunami water above the reference sea level at the coast. In extreme cases, tsunami run-up can exceed 30 metres.
3.4 Tides
Tides are the regular rise and fall of ocean water levels, mainly caused by the gravitational attraction of the Moon and the Sun, together with the motion of the Earth–Moon system.
Many coastal places experience two high tides and two low tides during a lunar day, although local tidal patterns differ.
High Tide (Flood Tide)
High tide is the stage when sea level reaches its highest level during a tidal cycle. Flood tide refers to the period when the water level is rising.
Low Tide (Ebb Tide)
Low tide is the stage when sea level reaches its lowest level during a tidal cycle. Ebb tide refers to the period when the water level is falling.
3.5 Spring Tides and Neap Tides
The difference between high and low water levels changes according to the relative positions of the Sun, Moon and Earth.
Spring Tides
Spring tides occur when the Sun, Moon and Earth are aligned approximately in a straight line, during the new moon and full moon.
The combined tide-producing effects of the Moon and Sun create a larger tidal range. High tides become higher and low tides become lower than usual.
Neap Tides
Neap tides occur during the first-quarter and third-quarter moon, when the directions towards the Moon and Sun are approximately at right angles as seen from Earth.
Their tidal effects partially oppose each other, producing a smaller difference between high and low tides.
Simplified representation of tidal forcing. Positions and water bulges are not to scale.
| Feature | Spring Tide | Neap Tide |
|---|---|---|
| Moon Phase | New moon and full moon | First and third quarters |
| Arrangement | Sun, Earth and Moon approximately aligned | Sun and Moon approximately at right angles relative to Earth |
| Tidal Range | Larger than usual | Smaller than usual |
| High Water | Higher than usual | Generally less high |
| Low Water | Lower than usual | Generally less low |
Imp for Exams
Spring tide does not mean a tide occurring only during the spring season. It refers to the larger tidal range produced when the tidal influences of the Sun and Moon reinforce each other.
3.6 Importance of Tides
1. Navigation and Harbour Activities
High tides raise water levels near shores and harbours, helping large ships enter or leave ports where the water may otherwise be too shallow.
Ship operators must check water depth and tidal range to avoid accidents. Some large oil tankers wait for favourable tides before passing through shallow channels, such as parts of the Singapore Strait.
Gulf of Khambhat
The chapter notes a tidal range of about 12 metres in the Gulf of Khambhat, Gujarat, which is among India's highest tidal ranges.
Tidal Currents
Large amounts of seawater moving in and out of coastal areas can produce tidal currents reaching about 5–6 knots (9–11 km/h).
2. Fishing
During high tide, fish may move closer to the shore in search of food and shelter. This helps fishing communities plan fishing activities and improve their catch.
3. Generation of Electricity
The rise and fall of tidal water can be used to generate electrical energy. Tidal energy is a renewable form of ocean energy.
Important tidal energy locations in India:
- Gulf of Kutch, Gujarat
- Gulf of Khambhat, Gujarat
- Sundarbans region
Although India has a long coastline, large-scale tidal electricity generation is still limited.
4. Coastal Access and Safety
The Bhadkeshwar Mahadev Temple at Dwarka, Gujarat, provides an example of how tides affect access to coastal locations. Its stone pathway becomes submerged during high tide and is accessible during low tide.
Imp Fact
The textbook reports India's coastline as approximately 11,098.81 kilometres. This extensive coastline offers opportunities for fishing, ports, tourism and ocean-energy development.
3.7 Ocean Currents
Ocean currents are continuous streams of ocean water flowing in definite directions. They transport enormous volumes of water and heat from one region of the Earth to another.
Factors Responsible for Ocean Currents
1. Prevailing Winds
Winds push surface water and help establish large ocean-current patterns.
2. Earth's Rotation
The Coriolis effect causes moving water to be deflected, influencing the direction of currents.
3. Temperature Differences
Temperature influences seawater density and helps drive large-scale ocean circulation.
4. Salinity Differences
Differences in the amount of dissolved salt affect water density and movement.
5. Shape of Continents and Ocean Basins
Coastlines, underwater ridges and ocean-basin boundaries redirect moving water.
Warm Currents and Cold Currents
| Basis | Warm Currents | Cold Currents |
|---|---|---|
| Origin | Carry relatively warm water, commonly from lower latitudes. | Carry relatively cold water, commonly from higher latitudes or regions of cold-water upwelling. |
| Coastal Climate | Generally make nearby coastal conditions warmer. | Generally make nearby coastal conditions cooler. |
| Map Colour | Usually shown in red. | Usually shown in blue. |
| Example | Gulf Stream | Labrador Current |
Example 1 — Gulf Stream
The Gulf Stream is a warm Atlantic Ocean current associated with warm waters from the Gulf of Mexico region. Along with its northeastward extension, it helps carry heat towards western and northern Europe.
As a result, parts of the Norwegian coast remain relatively warm and many coastal waters remain navigable despite their high latitude.
Example 2 — Labrador Current
The Labrador Current is a cold current flowing southward along eastern Canada. It transports cold water and icebergs into lower latitudes than would otherwise be expected.
Effects of Ocean Currents
Climate Regulation
Currents redistribute heat and affect coastal temperatures and weather conditions.
Marine Biodiversity
Currents transport nutrients and influence conditions for marine plants and animals.
Fishing Grounds
Regions where different water masses meet can support rich marine ecosystems and productive fisheries.
Ocean Transport
Ships consider ocean currents while planning routes, fuel consumption and travel times.
Important Fishing Grounds
Regions where warm and cold currents meet often contain productive fishing grounds. Mixing and associated nutrient-rich waters can support plankton, which forms the base of the marine food chain.
Ocean Currents Near India
Ocean currents around India are influenced strongly by the seasonal monsoon winds. Surface currents in parts of the Arabian Sea and Bay of Bengal change direction with the monsoon seasons, affecting fishing, navigation and the movement of marine nutrients.
4. Cyclones and Tsunamis—Early Warning Systems
Coastal areas may be exposed to powerful natural hazards such as cyclones, tsunamis and dangerous storm surges.
An Early Warning System (EWS) uses scientific instruments, communication technology and organised response procedures to detect hazards and warn communities before a disaster causes widespread damage.
Cyclone
A large rotating atmospheric storm that develops over warm ocean waters and may produce destructive winds, heavy rain and storm surges.
Tsunami
A series of powerful sea waves most commonly produced by sudden displacement of seawater due to underwater earthquakes.
4.1 Early Warning Systems in India
India operates cyclone-warning and marine-weather services along its eastern and western coasts. These services continuously observe oceanic and atmospheric conditions and communicate warnings to people in vulnerable areas.
Important Organisations and Programmes
| Organisation / Programme | Main Function |
|---|---|
| India Meteorological Department (IMD) | Monitors weather, forecasts cyclones and provides meteorological warnings. |
| Indian National Centre for Ocean Information Services (INCOIS) | Provides ocean information, tsunami warnings and marine advisories. |
| Indian Tsunami Early Warning Centre (ITEWC) | Detects possible tsunamis and issues warnings based on seismic and sea-level observations. |
| National Cyclone Risk Mitigation Project (NCRMP) | Improves cyclone shelters, warning systems and emergency preparedness in cyclone-prone areas. |
| Storm Surge Early Warning System (SSEWS) | Forecasts cyclone-related storm surges and possible flooding of coastal areas. |
| Decision Support System (DSS) | Helps disaster-management authorities interpret information and make timely decisions. |
4.2 GEMINI — Safety Information for Fishermen
GEMINI stands for GAGAN-Enabled Mariner's Instrument for Navigation and Information.
It is a handheld communication device designed to improve the safety of fishermen who travel into the sea.
How GEMINI Works
The GEMINI device receives satellite information and transfers it to a mobile phone using Bluetooth. The INCOIS mobile application then displays the information in regional languages.
Information Provided by GEMINI
- Warnings about high waves and strong winds
- Cyclone and tsunami alerts
- Potential fishing-zone advisories
- Ocean-current speeds
- Bathymetric information and maps
- Other information relevant to safety at sea
Existing Communication Range
The textbook describes a communication range of up to 50 nautical miles at the time of publication.
Proposed Upgrade
It describes plans for two-way communication and an extended operating range of up to 300 nautical miles.
Under the Pradhan Mantri Matsya Sampada Yojana (PMMSY), financial support is provided for GEMINI devices to improve the safety of fishing communities.
4.3 Focus on Cyclones
Cyclones develop due to atmospheric disturbances over warm ocean waters. Warm, moist air rises, surface pressure falls and surrounding air moves towards the low-pressure region.
Under suitable conditions, the system becomes organised and rotates because of Earth's rotation.
Naming of Cyclones
Cyclones in the North Indian Ocean are named using an agreed list prepared by participating countries.
The chapter states that the list contains 169 names contributed by 13 member countries.
Examples mentioned in the chapter include:
- Cyclone Biparjoy — 2023
- Cyclone Remal — 2024
Naming cyclones helps scientists, governments, media and the public communicate clearly about specific storms.
4.4 The 2004 Indian Ocean Tsunami
On 26 December 2004, a powerful undersea earthquake generated a devastating tsunami in the Indian Ocean.
The disaster affected several countries bordering the Indian Ocean and caused approximately 2,30,000 deaths.
India suffered widespread destruction, particularly in coastal and island areas.
Imp — Severely Affected Regions of India
- Tamil Nadu
- Puducherry
- Andhra Pradesh
- Keralam (Kerala)
- Andaman and Nicobar Islands
The disaster demonstrated the need for effective tsunami detection, faster public warnings, coastal evacuation plans and community awareness.
4.5 Functioning of the Tsunami Early Warning System
India uses a network of seismic monitoring instruments, underwater pressure recorders, sea-level gauges, communication satellites and warning centres.
These work together to identify possible tsunamis and provide warnings to vulnerable coastal communities.
The four major stages of detecting, verifying, monitoring and communicating tsunami threats.
Stage 1 — Detection
Seismic stations continuously monitor earthquakes. A strong underwater earthquake may indicate the possibility of a tsunami.
Stage 2 — Confirmation
Ocean Bottom Pressure Recorders (OBPRs) detect changes in underwater pressure associated with tsunami waves. These observations help confirm whether a tsunami has been generated.
Stage 3 — Tracking
Coastal tide gauges and other monitoring instruments measure unusual changes in sea level and help track the tsunami's movement and arrival.
Stage 4 — Warning Dissemination
The Indian Tsunami Early Warning Centre sends information to the Government of India and other responsible authorities.
Warnings are passed to state governments, emergency teams and the public through communication networks such as:
- Satellite-based communication
- SMS alerts
- Email notifications
- Coastal display boards
- Public-warning systems and official communication channels
4.6 Elements of the Tsunami Early Warning System
| Element | Purpose |
|---|---|
| Warning Centre | Analyses information and issues warnings. |
| Modelling and Simulation | Estimates possible tsunami movement and impacts. |
| Capacity Development | Prepares officials and communities to respond. |
| Communication Satellite | Transfers information between monitoring and warning systems. |
| GPS Satellite | Supports location and positioning services. |
| Tide Gauge Station | Measures changes in sea level. |
| GPS Station | Helps monitor ground movement and positioning. |
| Seismometer Station | Records vibrations produced by earthquakes. |
| Seismic Waves | Carry earthquake energy through the Earth. |
| Earthquake | May cause sudden seafloor displacement that generates a tsunami. |
4.7 Importance of Early Warning Systems
Scientific instruments are useful only when people receive warnings in time and know what actions to take.
Therefore, early warning systems must combine technology with community education, evacuation plans and disaster-response training.
Five Safety Steps During a Tsunami or Cyclone Warning
- Follow official instructions: Listen to verified alerts from disaster-management authorities.
- Move to a safer place: Evacuate when instructed. During a tsunami threat, move away from the coast to higher ground or inland.
- Carry emergency supplies: Take drinking water, medicines, a torch, essential documents and other necessary items if time permits.
- Protect vulnerable people: Help children, older persons and people with disabilities reach a safe location.
- Wait for official clearance: Do not return to dangerous areas until authorities announce that it is safe.
Additional tsunami precaution: If you are near the shore and feel a strong or long earthquake, move inland or to higher ground immediately without waiting for an official warning.
5. Marine Resources and Their Significance
Oceans contain a wide range of useful natural materials, organisms and energy sources.
Marine resources are the natural materials, living organisms and useful features found in oceans that have ecological, cultural or economic value.
Marine resources can broadly be classified into two categories:
Marine Living Resources
Resources obtained from living marine organisms, including fish, aquatic plants and other forms of marine life.
Marine Non-living Resources
Non-living materials and energy resources, including minerals, oil, natural gas and ocean energy.
5.1 Classification of Marine Resources
A simplified mind map showing the major groups of marine resources described in the chapter.
A. Marine Living Resources
Marine living resources include organisms such as fish, aquatic vegetation and other sea life. They provide food, useful biological products and support entire marine ecosystems.
| Category | Description |
|---|---|
| Fish | Fish caught for food and commercial purposes, including species living near the coast and in open oceans. |
| Bioactive Natural Products | Useful substances obtained from marine organisms, including compounds studied for medicines and other applications. |
| Marine Bio-organisms | Marine living organisms and microorganisms that form part of ocean ecosystems. |
| Submerged Aquatic Vegetation (SAV) | Aquatic plants growing underwater that provide habitats, food and environmental benefits. |
Coastal/Neritic Fish and Oceanic Fish
Coastal/Neritic Fish
Fish living in waters above the continental shelf, usually within depths of approximately 0–200 metres.
Oceanic Fish
Fish found beyond the continental shelf in the open ocean, where water may extend to depths greater than 200 metres.
Fish According to Their Habitat
| Group | Habitat |
|---|---|
| Epipelagic Fish | Fish that live in the sunlit upper layer of the open ocean. |
| Pelagic Fish | Fish living in the open-water region rather than directly on the seafloor. |
| Demersal Fish | Fish that live and feed on or close to the seabed. |
| Benthopelagic Fish | Fish associated with the water layer immediately above the ocean floor. |
| Benthic Fish | Fish living on the ocean bottom. |
B. Marine Non-living Resources
Marine non-living resources include minerals, sediments, fossil fuels and renewable energy available from oceans.
Minerals and Materials
Sand, gravel and deep-sea mineral deposits are used or studied for construction, industry and other economic purposes.
Energy Resources
Oceans provide conventional energy such as oil and natural gas, along with renewable sources such as tides, waves and ocean currents.
Classification of Marine Energy
| Energy Type | Examples | Source |
|---|---|---|
| Conventional | Petroleum and natural gas | Deposits beneath the ocean floor |
| Tidal Energy | Tidal electricity | Movement of tidal water |
| Wave Energy | Wave-energy devices | Energy carried by ocean waves |
| Current Energy | Underwater current turbines | Flowing ocean water |
| Offshore Wind Energy | Wind turbines at sea | Wind blowing over marine areas |
| Ocean Thermal Energy | Ocean Thermal Energy Conversion (OTEC) | Temperature difference between warm surface water and deep cold water |
| Gas Hydrates | Methane hydrates | Gas trapped within ice-like substances in suitable marine sediments |
| Biofuels | Fuel produced from marine biomass | Suitable algae and other biological materials |
5.2 Significance of Marine Resources
Marine resources are essential for food security, livelihoods, economic development, trade, energy and environmental protection.
1. Food and Livelihood
Fish and other seafood provide protein and nutrients to millions of people. Fishing and aquaculture create employment for fishermen, fish traders, transport workers and food-processing industries.
2. Energy
Offshore oil and natural gas support industries and transportation. Renewable marine energy, including tidal and wave power, offers possibilities for future electricity production.
3. Minerals and Materials
Sand, gravel and deep-sea mineral resources have various industrial uses. However, extraction can damage marine ecosystems and therefore requires careful planning and regulation.
4. Trade and Tourism
Shipping connects producers and consumers across the world. The chapter notes that approximately 90% of global trade by volume is transported by sea.
Coastal tourism also supports hotels, restaurants, transport services and local businesses.
5. Environmental Importance
Marine ecosystems provide habitats for countless organisms, support food chains and help regulate Earth's climate.
Coral reefs, underwater vegetation and other marine habitats are important for biodiversity and coastal protection.
6. Cultural Significance
Oceans have influenced Indian traditions, occupations, stories and religious practices.
The śhaṅkha (conch shell) and kapardikā (cowrie shells) are examples of marine objects with cultural significance. Cowrie shells were also used as a form of currency in the past.
Indian mythology connects ocean treasures with the story of Samudra Manthana.
Imp for Exams — Importance of Marine Resources
Marine resources provide food, employment, minerals, energy and opportunities for international trade. They support biodiversity and coastal cultures. Their careful use is necessary to maintain a healthy ocean environment for present and future generations.
5.3 Blue Economy is the Future: Sustainable Growth Powered by Healthy Oceans
The Blue Economy refers to the sustainable use of ocean resources to support economic development, improve livelihoods and create employment while maintaining the health of marine ecosystems.
It connects economic benefits with environmental protection.
Blue Economy and Sustainable Development Goal 14
The United Nations Sustainable Development Goal SDG 14 — Life Below Water focuses on protecting oceans and using marine resources sustainably.
| Goal | Explanation |
|---|---|
| Reduce Marine Pollution | Prevent harmful waste, plastics and chemicals from entering oceans. |
| Protect Marine Ecosystems | Conserve habitats and species and restore damaged marine environments. |
| Address Ocean Acidification | Reduce the causes and effects of increasing ocean acidity. |
| Regulate Fishing | Control overfishing and promote sustainable fishing practices. |
| Conserve Marine Areas | Protect ecologically important coastal and ocean regions. |
| Eliminate Harmful Subsidies | Reduce financial support that encourages unsustainable fishing. |
| Increase Economic Benefits | Help coastal communities and countries benefit fairly from sustainable ocean use. |
How Can Marine Resources Be Used Sustainably?
- Prevent excessive and illegal fishing.
- Reduce marine pollution and plastic waste.
- Protect coral reefs, mangroves and breeding grounds.
- Use renewable ocean-energy resources where environmentally suitable.
- Control damaging activities such as irresponsible seabed extraction.
- Strengthen international cooperation and marine conservation laws.
6. Maritime Zones
Oceans connect many countries, but different areas of the sea are governed by different legal rules.
Maritime zones are regions of the sea defined under international law to determine the rights, responsibilities and jurisdiction of coastal countries.
These zones help countries regulate navigation, resource use, immigration, customs and environmental protection.
6.1 Major Maritime Zones
Simplified representation of legal maritime zones. Distances are measured from the baseline; the continental shelf has separate legal rules.
| Zone | Extent | Rights and Characteristics |
|---|---|---|
| Internal Waters | Landward of the baseline | The coastal country generally exercises sovereignty over these waters, subject to applicable international rules. |
| Territorial Sea | Up to 12 nautical miles | The coastal country exercises sovereignty, subject to innocent passage and other international-law conditions. |
| Contiguous Zone | Up to 24 nautical miles from the baseline | The coastal country has limited powers related to customs, fiscal matters, immigration and sanitation. |
| Exclusive Economic Zone (EEZ) | Up to 200 nautical miles from the baseline | The coastal country has sovereign rights to explore, use, conserve and manage natural resources, while other states retain certain freedoms. |
| Continental Shelf | Generally at least 200 nautical miles for legal purposes; may extend farther where UNCLOS conditions are met | The coastal country has sovereign rights over seabed and subsoil resources, subject to international law. |
| High Seas | Waters beyond national EEZs | No country has sovereignty over these waters. States enjoy freedoms governed by international law. |
6.2 Territorial Sea
The territorial sea extends up to 12 nautical miles from the baseline.
Within this zone, a coastal country exercises sovereignty over the water, airspace, seabed and subsoil, subject to international law.
The government can regulate activities such as customs, immigration, pollution control and maritime safety.
However, foreign ships generally have a right called innocent passage, provided they meet the relevant conditions.
Innocent Passage
Innocent passage allows a foreign ship to travel through another country's territorial sea without threatening that country's peace, good order or security.
Passage must ordinarily be continuous and expeditious, although stopping or anchoring may be permitted when incidental to ordinary navigation, necessary because of distress or force majeure, or required to assist people or vessels in danger.
Imp Conditions of Innocent Passage
- The passage must remain peaceful and must not threaten coastal security.
- The ship must not carry out unauthorised fishing activities.
- Military exercises or weapons practice are not permitted as innocent passage.
- The ship must comply with applicable navigation and safety requirements.
- The passage must not involve other activities prejudicial to the peace, good order or security of the coastal country.
6.3 Contiguous Zone
The contiguous zone extends up to 24 nautical miles from the baseline, including the territorial sea.
In the area beyond the territorial sea, the coastal country can exercise limited control necessary to prevent or punish certain violations of its laws, particularly concerning:
- Customs
- Fiscal matters and taxation
- Immigration
- Sanitation
These are specific enforcement powers, not complete ownership of all waters in the zone.
6.4 Exclusive Economic Zone (EEZ)
The Exclusive Economic Zone extends up to 200 nautical miles from the baseline.
It is recognised under the United Nations Convention on the Law of the Sea (UNCLOS).
Within its EEZ, a coastal country has special sovereign rights relating to the exploration, conservation, management and economic use of natural resources.
Rights of the Coastal Country in the EEZ
- Explore, conserve and manage fisheries and other living marine resources.
- Explore and exploit offshore oil, natural gas and other non-living resources.
- Use resources for energy production, including energy from water, currents and winds.
- Exercise jurisdiction over certain artificial islands, installations and structures.
- Regulate certain marine scientific research activities.
- Protect and preserve the marine environment according to international law.
Imp Distinction
An Exclusive Economic Zone is not the same as territorial waters. A coastal country has special resource-related rights in its EEZ, but it does not have complete sovereignty over the entire water area. Other countries retain internationally recognised freedoms, including navigation and overflight.
6.5 High Seas
The high seas are ocean waters lying beyond the EEZs of coastal countries.
They form part of the global commons, meaning that no country can claim sovereignty over these waters.
The textbook notes that the high seas cover approximately 64% of the world's oceans.
Freedoms of the High Seas
Subject to international-law conditions, countries may exercise freedoms including:
- Navigation of ships
- Overflight by aircraft
- Fishing in accordance with conservation rules
- Laying submarine cables and pipelines
- Marine scientific research
- Constructing installations permitted by international law
Problems Associated with the High Seas
Because the high seas are not controlled by one coastal government, ensuring compliance with rules can be difficult.
Major challenges include:
- Overfishing
- Illegal fishing
- Pollution
- Conflicts over the use of resources
- Difficulty in monitoring some activities and enforcing laws
Ships are generally subject to the jurisdiction of their flag state, which is the country where the ship is registered.
6.6 Importance of Maritime Zones
National Security
Maritime boundaries help governments protect coastal waters and regulate activities near their coasts.
Economic Development
Coastal countries can manage fisheries, energy resources and offshore economic activities.
Resource Management
Defined rights help countries conserve, manage and use marine resources responsibly.
Peaceful Cooperation
International agreements provide a legal framework for resolving maritime boundary and resource disputes.
7. International Maritime Rules and Regulations
Oceans are important routes for transport, international trade, fishing and communication.
Ships travelling across different parts of the world must follow internationally recognised rules to prevent accidents, reduce pollution and protect human life.
Maritime law and maritime regulations are legal rules and international agreements governing activities at sea.
7.1 Important Maritime Rules and Regulations
A. UNCLOS — United Nations Convention on the Law of the Sea
UNCLOS establishes an international legal framework for different maritime zones, navigation rights, marine resources and the peaceful settlement of maritime disputes.
It helps define coastal-state rights and the responsibilities of countries using the oceans.
B. COLREGs — Convention on the International Regulations for Preventing Collisions at Sea
COLREGs contain internationally recognised rules designed to prevent ships from colliding.
These are similar in purpose to traffic rules on roads, but are designed for vessels travelling on water.
Important COLREGs Requirements
- Proper Lookout: Ships must maintain a proper lookout to detect nearby vessels and possible dangers.
- Safe Speed: Ships should travel at speeds that allow enough time to respond to hazards.
- Collision Avoidance: Vessels must take appropriate and timely action to avoid collisions.
- Give-way and Stand-on Vessels: Rules define which vessel must take avoiding action and which should normally maintain course and speed in specified situations.
- Lights and Shapes: Navigation lights and day shapes help other vessels identify a ship's status and activities.
- Sound Signals: Sound signals are used in certain navigation situations, including reduced visibility.
Give-way Vessel: A vessel required by the applicable collision-prevention rules to take early and substantial action to keep clear of another vessel.
Stand-on Vessel: A vessel that should normally maintain its course and speed under the relevant rules, while remaining ready to act if necessary to avoid collision.
C. MARPOL — International Convention for the Prevention of Pollution from Ships
MARPOL is an important international agreement aimed at preventing and reducing pollution caused by ships.
It establishes requirements for controlling pollution from ship operations and certain accidental discharges.
Pollution sources regulated under MARPOL include oil, harmful liquid substances, sewage, garbage and air emissions from ships.
| Convention | Full Name | Main Purpose |
|---|---|---|
| UNCLOS | United Nations Convention on the Law of the Sea | Defines maritime rights, zones and responsibilities. |
| COLREGs | Convention on the International Regulations for Preventing Collisions at Sea | Prevents collisions and promotes safe navigation. |
| MARPOL | International Convention for the Prevention of Pollution from Ships | Prevents and reduces ship-generated pollution. |
7.2 Why are Maritime Rules Important?
International maritime rules establish common standards for countries and ships operating in the oceans.
They are important for the following reasons:
1. Safe Navigation
Common navigation rules reduce the risk of collisions and other accidents at sea.
2. Pollution Prevention
Pollution-control conventions help protect water quality, marine organisms and coastal environments.
3. Protection of Human Life
Safety regulations reduce risks to sailors, passengers and fishing communities.
4. Fair Resource Use
International rules help define who may use marine resources and under what conditions.
5. International Cooperation
Agreements establish methods for avoiding and resolving disputes among countries.
6. Protection of Trade
Reliable sea routes enable the safe and efficient movement of goods between countries.
Imp for Exams — Maritime Rules
UNCLOS deals mainly with the legal framework of ocean use and maritime rights. COLREGs deal with collision prevention and safe navigation. MARPOL deals with preventing pollution from ships.
8. Questions and Activities — Written Answers
The following answers address the chapter's written conceptual questions. Practical activities and projects are omitted.
The ocean floor contains different landforms such as continental shelves, continental slopes, abyssal plains, ridges, seamounts and trenches. These features influence human activities in several ways.
- Fishing: Continental shelves are shallow areas rich in nutrients and marine life. They provide important fishing grounds and support the livelihoods of coastal communities.
- Transport: Underwater features affect the depth of navigable waters. Ships need reliable ocean-depth information to avoid submerged obstacles and shallow regions.
- Underwater Exploration: Scientists study mid-ocean ridges, trenches and seamounts to understand underwater volcanoes, tectonic movements and deep-sea organisms.
- Resource Extraction: Continental shelves contain valuable resources such as petroleum and natural gas. Other regions contain minerals and materials of economic interest.
- Marine Ecosystems: Different ocean-floor features provide habitats for different organisms, influencing biodiversity and the distribution of marine resources.
Thus, ocean relief plays an important role in fishing, navigation, resource extraction and scientific research.
Waves, tides and ocean currents are the major forms of ocean-water movement. They affect the environment and several human activities.
1. Waves
- Waves erode coastlines and form landforms such as sea caves, arches, stacks and stumps.
- They deposit sediments and help form beaches.
- Storm waves can damage ports, fishing boats and coastal settlements.
- Wave action also influences nearshore marine habitats and the movement of sediments and nutrients.
2. Tides
- High tides raise the water level, helping ships enter and leave certain harbours.
- Tides influence fishing because some fish move closer to the coast during high tide.
- Tidal movements can be used to produce renewable electricity.
- Tidal flooding and currents influence coastal habitats and activities.
3. Ocean Currents
- Warm currents raise temperatures in some coastal regions, while cold currents lower them.
- Currents redistribute heat and influence climate and weather.
- They transport nutrients and help support productive fishing grounds.
- They affect the routes and travel times of ships.
Conclusion: Waves mainly shape coasts, tides influence sea levels and coastal activities, and currents redistribute ocean water and heat. Together, these movements strongly influence marine life, climate, transport and livelihoods.
Marine resources include living and non-living materials obtained from oceans. They are important for human life, economic development and environmental balance.
- Food: Fish and other seafood provide protein and nutrients to large populations.
- Employment: Fishing, aquaculture, transport, processing and tourism provide employment to millions of people.
- Energy: Offshore oil, natural gas, tidal energy and wave energy are important energy resources.
- Minerals: Oceans contain sand, gravel and deep-sea mineral deposits used in or studied for industrial purposes.
- Trade: Oceans support international shipping and enable the movement of goods around the world.
- Tourism: Beaches, islands and coastal attractions generate income for local communities.
- Biodiversity: Marine ecosystems support numerous species and help maintain ecological balance.
- Cultural Value: Oceans have influenced traditions, religious practices and the history of coastal societies.
Therefore, marine resources must be used sustainably to support human development while protecting ocean ecosystems for future generations.
The principle is called Innocent Passage.
Under this principle, a foreign ship may pass through India's territorial sea if its passage does not threaten India's peace, good order or security.
The ship must follow applicable maritime rules and should not conduct activities such as unauthorised fishing, weapons exercises or other actions that make its passage non-innocent.
Passage must ordinarily be continuous and expeditious, subject to recognised exceptions such as emergencies.
Therefore, innocent passage allows foreign ships to travel peacefully through the territorial waters of a coastal country under the conditions established by international law.
Within its Exclusive Economic Zone (EEZ), a coastal country has sovereign rights to explore, exploit, conserve and manage natural resources.
These rights include:
- Fishing Rights: The country can regulate fishing and manage living marine resources.
- Oil and Natural Gas: It can explore and use petroleum and natural-gas resources.
- Mineral Resources: It has rights over relevant mineral resources in the seabed and subsoil.
- Energy Production: It may produce energy from water, currents and winds.
- Marine Conservation: It can implement measures to protect and conserve marine resources.
- Research and Installations: It has specified jurisdiction concerning marine scientific research and artificial installations.
However, the EEZ is not fully owned like territorial waters. Other countries retain freedoms of navigation and overflight in accordance with international law.
Therefore, the EEZ gives a coastal country special economic and resource-management rights without granting it complete sovereignty over all the waters.