Archipelagic Waters

Introduction

Archipelagic waters are the waters enclosed by archipelagic baselines drawn by a qualifying archipelagic State under Part IV of the United Nations Convention on the Law of the Sea (UNCLOS).

The archipelagic State exercises sovereignty over these waters, as well as over the airspace above them and their seabed and subsoil. However, this sovereignty is subject to important rights of other States, particularly the rights of innocent passage and archipelagic sea lanes passage.

The principal legal framework is Part IV of UNCLOS, Articles 46–54.

Core Formula

Archipelagic State → Archipelagic Baselines → Archipelagic Waters → Sovereignty + Passage Rights

Meaning of Archipelagic State

The concept of archipelagic waters is based on the legal status of an archipelagic State.

Article 46(a) UNCLOS

An archipelagic State means a State constituted wholly by one or more archipelagos and may include other islands.

An archipelago is a group of islands, including parts of islands, interconnecting waters and other natural features which are so closely interrelated that they form an intrinsic geographical, economic and political entity, or which historically have been regarded as such.

Therefore, a State having several islands is not automatically an archipelagic State under UNCLOS.

Examples of Archipelagic States

Examples include:

• Indonesia
• Philippines
• Fiji
• Maldives
• Bahamas

The important point is that the State must satisfy the requirements of Article 46.

Legal Basis

The main provisions are:

• Article 46 → Definitions
• Article 47 → Archipelagic baselines
• Article 48 → Measurement of maritime zones
• Article 49 → Legal status of archipelagic waters
• Article 50 → Internal waters
• Article 51 → Existing agreements and traditional rights
• Article 52 → Innocent passage
• Article 53 → Archipelagic sea lanes passage
• Article 54 → Application of Articles 39, 40 and 42

Archipelagic Baselines

Article 47 UNCLOS

The most important feature of the archipelagic regime is the system of archipelagic baselines.

An archipelagic State may draw straight archipelagic baselines joining the outermost points of the outermost islands and drying reefs of the archipelago.

The waters enclosed by these baselines become the State’s archipelagic waters.

Why Archipelagic Baselines Are Needed

An archipelagic State may consist of hundreds or thousands of islands separated by extensive areas of water.

Applying ordinary coastal baselines to each individual island could produce a fragmented maritime regime.

UNCLOS therefore provides a special system allowing the State to draw baselines around the archipelago as a whole.

Ordinary Coastal State

Coast → Baseline → Maritime Zones

Archipelagic State

Outer Islands → Archipelagic Baselines → Archipelagic Waters + Maritime Zones

Conditions for Archipelagic Baselines

Article 47 imposes strict geographical conditions.

Water-to-Land Ratio

The ratio of the area of water to the area of land, including atolls, enclosed by the baselines must generally be between:

1:1 and 9:1

Therefore:

Water : Land = 1:1 to 9:1

Length of Archipelagic Baselines

The length of an archipelagic baseline generally must not exceed:

100 nautical miles

However, up to 3% of the total number of baselines may exceed 100 nautical miles, subject to a maximum length of:

125 nautical miles

Memory Rule

1:9 – 100 – 125

• 1:9 → water-to-land ratio
• 100 nm → general maximum baseline length
• 125 nm → exceptional maximum

General Configuration of the Archipelago

Archipelagic baselines must not be drawn in a manner that departs appreciably from the general configuration of the archipelago.

This prevents an archipelagic State from manipulating the baseline system to enclose disproportionately large areas of water.

Article 48 – Measurement of Maritime Zones

The breadth of the:

• territorial sea;
• contiguous zone;
• EEZ;
• continental shelf

is measured from the archipelagic baselines, in accordance with UNCLOS.

Thus, the archipelagic baseline becomes the principal reference line for determining the State’s maritime entitlements.

Article 49 – Legal Status of Archipelagic Waters

Article 49 is the central provision concerning the legal status of archipelagic waters.

The sovereignty of an archipelagic State extends to:

• archipelagic waters;
• the airspace above them;
• their seabed;
• their subsoil;
• the resources contained therein.

Therefore:

Archipelagic Waters = Sovereignty

But the sovereignty is subject to the provisions of UNCLOS, particularly the rights of passage.

Sovereignty Is Not Absolute

The archipelagic State cannot exercise sovereignty in exactly the same way as if no international navigation rights existed.

Its sovereignty is subject to:

• innocent passage;
• archipelagic sea lanes passage;
• existing agreements;
• traditional fishing rights;
• other applicable UNCLOS obligations.

Archipelagic Waters vs Internal Waters

This is one of the most important distinctions.

Both are subject to the sovereignty of the State, but their legal regimes are different.

Internal Waters

Generally:

No general right of innocent passage

Archipelagic Waters

There is:

Right of innocent passage

and, where applicable:

Right of archipelagic sea lanes passage

Therefore:

Archipelagic waters are not simply internal waters on a larger scale.

Article 50 – Internal Waters

Article 50 preserves the right of an archipelagic State to delimit its internal waters within the archipelagic waters in accordance with UNCLOS.

Consequently, particular areas within the archipelagic system may have the legal status of internal waters.

Article 51 – Existing Rights

An archipelagic State must respect certain pre-existing rights.

These include:

• existing agreements with other States;
• traditional fishing rights of immediately adjacent neighbouring States in certain areas;
• existing submarine cables belonging to other States.

Traditional Fishing Rights

Where neighbouring States have traditionally fished in particular areas within archipelagic waters, the archipelagic State must recognise and respect those traditional rights under Article 51.

These rights are subject to the conditions established by UNCLOS and do not amount to a general right of fishing for all foreign States.

Submarine Cables

Existing submarine cables laid by other States must also be respected.

The archipelagic State must permit their maintenance and replacement, subject to the applicable UNCLOS rules.

Innocent Passage

Article 52 UNCLOS

Ships of all States enjoy the right of innocent passage through archipelagic waters.

This resembles innocent passage through the territorial sea.

The passage must be:

• continuous;
• expeditious;
• not prejudicial to the peace, good order or security of the archipelagic State.

Meaning of Innocent Passage

Passage is not innocent if the foreign ship engages in activities prejudicial to the peace, good order or security of the archipelagic State.

Examples include activities such as:

• threat or use of force;
• weapons exercises;
• intelligence gathering;
• certain fishing activities;
• research or survey activities;
• serious pollution;
• interference with communications.

Article 53 – Archipelagic Sea Lanes Passage

The distinctive feature of the archipelagic regime is archipelagic sea lanes passage.

An archipelagic State may designate:

• sea lanes;
• air routes

suitable for the continuous and expeditious passage of foreign ships and aircraft through or over its archipelagic waters and adjacent territorial sea.

Ships and Aircraft

This is a major distinction.

Innocent Passage

Primarily concerns:

Ships

Archipelagic Sea Lanes Passage

Includes:

Ships + Aircraft

Therefore:

Archipelagic Sea Lanes Passage = Ships + Aircraft

Purpose of Sea Lanes Passage

The sea-lanes system balances two competing interests:

Archipelagic State

Sovereignty over its waters

and

International Community

International navigation and overflight

The purpose is to ensure that international routes through an archipelago remain available.

Designation of Sea Lanes

The archipelagic State may designate sea lanes and air routes suitable for the continuous and expeditious passage of foreign ships and aircraft.

The designation must provide routes through or over the archipelagic waters and adjacent territorial sea.

If No Sea Lanes Are Designated

Where the archipelagic State does not designate sea lanes or air routes, the right of archipelagic sea lanes passage may still be exercised through routes normally used for international navigation, in accordance with Article 53.

Therefore:

No designation ≠ No passage right

Normal Mode of Transit

Ships and aircraft exercising archipelagic sea lanes passage must proceed in their normal mode of continuous and expeditious transit.

This is particularly important for submarines and aircraft.

Submarines

This creates an important distinction.

Innocent Passage

A submarine generally must:

Navigate on the surface + show its flag

Archipelagic Sea Lanes Passage

A submarine may:

Navigate in its normal mode

Therefore, a submarine may remain submerged while exercising archipelagic sea lanes passage.

Aircraft

Aircraft do not have a general right of innocent passage through territorial seas in the same way as ships.

However, aircraft are expressly covered by:

Archipelagic Sea Lanes Passage

This makes Article 53 particularly important.

Article 54

Article 54 applies Articles 39, 40 and 42 to archipelagic sea lanes passage.

These provisions concern matters such as:

• duties during passage;
• research and survey;
• laws and regulations of the coastal/archipelagic State.

Duties During Sea Lanes Passage

Ships and aircraft exercising archipelagic sea lanes passage must:

• proceed without delay;
• refrain from threats or use of force inconsistent with the UN Charter;
• refrain from activities other than those incidental to their normal mode of transit;
• comply with applicable international law.

Research and Survey

Foreign ships exercising archipelagic sea lanes passage cannot conduct marine scientific research or hydrographic surveys without authorisation.

This protects the security and sovereign interests of the archipelagic State.

Laws of the Archipelagic State

The archipelagic State may adopt laws and regulations concerning archipelagic sea lanes passage in accordance with UNCLOS.

However, those regulations cannot:

• deny the right of passage;
• hamper passage;
• discriminate among foreign ships;
• have the practical effect of denying or impairing passage.

Suspension of Passage

The archipelagic State cannot freely suspend archipelagic sea lanes passage merely because it considers the passage inconvenient.

The regime is designed to protect international navigation through archipelagic waters.

This is different from the limited circumstances in which innocent passage may be suspended under the applicable UNCLOS rules.

Archipelagic Waters and Territorial Sea

The territorial sea of an archipelagic State is measured from its archipelagic baselines.

Therefore:

Inside Archipelagic Baselines

→ Archipelagic Waters

Outside Baselines

→ Territorial Sea, up to 12 nautical miles

Archipelagic Waters and EEZ

The EEZ is also measured from the relevant archipelagic baselines.

It may extend up to:

200 nautical miles

subject to applicable delimitation rules.

Archipelagic Waters and Continental Shelf

Continental-shelf entitlements are also determined under UNCLOS with reference to the applicable baselines.

The archipelagic regime therefore has an important effect on the geographical measurement of maritime zones.

Archipelagic Waters and High Seas

The waters enclosed by valid archipelagic baselines are not high seas.

They are subject to the sovereignty of the archipelagic State under Article 49.

Archipelagic State vs Island State

This distinction is frequently examined.

Island State

A State may have one or more islands.

Archipelagic State

A State must satisfy the specific definition under Article 46 and qualify for the archipelagic baseline regime under Article 47.

Therefore:

Every archipelagic State is an island-based State, but every island State is not necessarily an archipelagic State.

Archipelagic Baselines vs Straight Baselines

These are separate concepts.

Straight Baselines

Article 7

Used by coastal States in certain geographical circumstances.

Archipelagic Baselines

Article 47

Used by qualifying archipelagic States to enclose the archipelago as a whole.

They should not be treated as interchangeable.

Archipelagic Waters and Fisheries

The archipelagic State exercises sovereignty over archipelagic waters and their resources, subject to applicable international law.

However, Article 51 protects certain traditional fishing rights of immediately adjacent neighbouring States.

This reflects a balance between:

• archipelagic-State sovereignty;
• pre-existing local fishing interests.

Archipelagic Waters and Marine Resources

The sovereignty of the archipelagic State extends to resources in the archipelagic waters, seabed and subsoil.

This differs from the EEZ.

Archipelagic Waters

Sovereignty

EEZ

Sovereign Rights

Archipelagic Waters and Marine Scientific Research

Foreign scientific research activities are subject to the applicable UNCLOS rules.

The existence of archipelagic sea lanes passage does not create an unrestricted right to conduct scientific research or hydrographic surveys.

Environmental Protection

The archipelagic State must exercise its rights consistently with the marine environmental obligations established by UNCLOS.

Part XII of UNCLOS contains broader obligations concerning:

• protection of the marine environment;
• prevention of pollution;
• conservation;
• international cooperation.

Archipelagic Waters and Warships

Foreign warships may exercise passage rights in accordance with the applicable UNCLOS regime.

The fact that a vessel is a warship does not automatically eliminate the navigation rights recognised by Part IV.

The legality of the passage depends on:

• the applicable passage regime;
• the conduct of the vessel;
• compliance with UNCLOS.

Archipelagic Waters and Submarines

This is a useful examination point.

Innocent Passage

Submarine → Surface

Archipelagic Sea Lanes Passage

Submarine → Normal mode, including submerged navigation

Archipelagic Waters and Aircraft

Innocent Passage

Aircraft are not given a general equivalent right.

Archipelagic Sea Lanes Passage

Aircraft:

Have a protected passage right

subject to Article 53 and related provisions.

Archipelagic Sea Lanes Passage vs Transit Passage

These concepts are similar but arise in different geographical circumstances.

Transit Passage

Applies to:

International straits

under Part III.

Archipelagic Sea Lanes Passage

Applies to:

Archipelagic States

under Part IV.

Both protect continuous and expeditious international navigation, but they are legally distinct regimes.

Comparison

Transit Passage	Archipelagic Sea Lanes Passage
Part III UNCLOS	Part IV UNCLOS
International straits	Archipelagic waters
Ships + aircraft	Ships + aircraft
Continuous and expeditious	Continuous and expeditious
Submarines may remain submerged	Submarines may remain submerged
Applies through international straits	Applies through archipelagic sea lanes/routes

Archipelagic Waters vs Internal Waters

Archipelagic Waters	Internal Waters
Part IV	General internal-waters regime
Sovereignty	Sovereignty
Innocent passage applies	No general innocent passage
Archipelagic sea lanes passage may apply	No equivalent general regime
Special international navigation rights	Stronger coastal-State control

Archipelagic Waters vs Territorial Sea

Archipelagic Waters	Territorial Sea
Inside archipelagic baselines	Outside baseline
Sovereignty	Sovereignty
Part IV	Part II
Innocent passage	Innocent passage
Special archipelagic sea lanes passage	Transit passage where international straits rules apply

Archipelagic Waters vs EEZ

Archipelagic Waters	EEZ
Sovereignty	Sovereign rights
Inside archipelagic baselines	Up to 200 nm
Airspace under sovereignty	Foreign overflight freedom
Special passage regime	Navigation freedoms
Part IV	Part V

Archipelagic Baseline Memory

1:9 – 100 – 125

1:9

→ Water-to-land ratio

100 nm

→ General maximum baseline length

125 nm

→ Exceptional maximum

Passage Memory

52 – 53

Article 52

→ Innocent Passage

Article 53

→ Archipelagic Sea Lanes Passage

And:

Sea Lanes = Ships + Aircraft

Article 49 Memory

“Water + Air + Seabed + Subsoil”

Article 49 sovereignty extends to:

• archipelagic waters;
• airspace;
• seabed;
• subsoil;
• resources.

But:

Sovereignty + International Passage Rights

Important UNCLOS Articles

Article 46

Definitions

Article 47

Archipelagic Baselines

Article 48

Measurement of Maritime Zones

Article 49

Legal Status and Sovereignty

Article 50

Internal Waters

Article 51

Existing Agreements and Traditional Rights

Article 52

Innocent Passage

Article 53

Archipelagic Sea Lanes Passage

Article 54

Application of Articles 39, 40 and 42

Important Numerical Rules

1:9

Water-to-land ratio

100 nm

General maximum length of an archipelagic baseline

125 nm

Maximum length permitted for the limited exceptional baselines

12 nm

Maximum territorial sea

200 nm

Maximum EEZ

Common Examination Mistakes

Mistake 1: Archipelagic Waters Are Internal Waters

Incorrect.

They are subject to sovereignty but have special international passage rights.

Mistake 2: Every Island State Is an Archipelagic State

Incorrect.

The Article 46 definition must be satisfied.

Mistake 3: Archipelagic Baselines Can Be Drawn Without Restrictions

Incorrect.

Article 47 imposes strict geographical and numerical conditions.

Mistake 4: The Water-to-Land Ratio Is 9:1

Be precise.

The ratio of water to land must generally be between:

1:1 and 9:1

Mistake 5: Every Baseline Can Be 125 Nautical Miles

Incorrect.

The general maximum is 100 nm, with limited exceptions allowing some baselines to exceed 100 nm up to 125 nm.

Mistake 6: Archipelagic Waters Have No Passage Rights

Incorrect.

Both innocent passage and archipelagic sea lanes passage are recognised.

Mistake 7: Aircraft Have Innocent Passage

Incorrect.

The significant aircraft passage regime is archipelagic sea lanes passage.

Mistake 8: Submarines Must Always Surface

Incorrect.

They must generally surface during innocent passage, but may navigate submerged during archipelagic sea lanes passage.

Mistake 9: Archipelagic State Has Unlimited Sovereignty

Incorrect.

Its sovereignty is subject to UNCLOS and international navigation rights.

Mistake 10: Archipelagic Sea Lanes Passage Can Be Freely Suspended

Incorrect.

It is a protected international navigation regime.

Mistake 11: Archipelagic Baselines Are the Same as Straight Baselines

Incorrect.

Article 47 and Article 7 establish different baseline systems.

Quick Revision

• Archipelagic waters → Part IV UNCLOS.
• Main provisions → Articles 46–54.
• Article 46 → definitions.
• Article 47 → archipelagic baselines.
• Article 48 → measurement of maritime zones.
• Article 49 → sovereignty over archipelagic waters.
• Article 50 → internal waters.
• Article 51 → existing agreements and traditional rights.
• Article 52 → innocent passage.
• Article 53 → archipelagic sea lanes passage.
• Article 54 → Articles 39, 40 and 42.
• Archipelagic State must satisfy Article 46.
• Archipelagic baselines join outermost points of outermost islands and drying reefs.
• Water-to-land ratio → 1:1 to 9:1.
• General baseline length → 100 nm.
• Limited exceptional baselines → up to 125 nm.
• Archipelagic waters are enclosed by valid archipelagic baselines.
• Archipelagic State exercises sovereignty over:
  • waters;
  • airspace;
  • seabed;
  • subsoil;
  • resources.
• Sovereignty is subject to UNCLOS passage rights.
• Foreign ships have innocent passage.
• Foreign ships and aircraft have archipelagic sea lanes passage where applicable.
• Submarines may remain submerged during archipelagic sea lanes passage.
• Existing agreements and traditional fishing rights may have to be respected.
• Existing submarine cables are protected under Article 51.
• Archipelagic waters are not identical to internal waters.
• Archipelagic waters are not the high seas.
• Archipelagic State is not simply any State with islands.
• Archipelagic baselines are different from straight baselines.
• Maritime zones are measured from the relevant archipelagic baselines.
• Archipelagic Waters → Sovereignty
• EEZ → Sovereign Rights
• Article 52 → Innocent Passage
• Article 53 → Sea Lanes Passage
• Sea Lanes → Ships + Aircraft
• Important related concepts:
  • innocent passage;
  • transit passage;
  • archipelagic sea lanes passage;
  • internal waters;
  • EEZ;
  • territorial sea.
• Key memory formula:

1:9 – 100 – 125 – 52 – 53

One-Line Memory Trick

Archipelagic Waters

“47 – 49 – 52 – 53”

47 → Baselines

49 → Sovereignty

52 → Innocent Passage

53 → Sea-Lanes Passage

And:

“1:9 – 100 – 125”

1:9 → Water-to-land ratio

100 nm → General baseline limit

125 nm → Exceptional limit

Final Maritime-Zone Formula

Archipelagic Baseline → Archipelagic Waters → Territorial Sea → Contiguous Zone → EEZ

Inside Archipelagic Baselines

→ Archipelagic Waters

→ Sovereignty

→ Innocent Passage

→ Archipelagic Sea Lanes Passage

↓

Up to 12 nm

→ Territorial Sea

↓

Up to 24 nm

→ Contiguous Zone

↓

Up to 200 nm

→ EEZ

↓

Beyond applicable national maritime zones

→ High Seas

Conclusion

Archipelagic waters are a distinctive creation of modern international law of the sea designed for States composed wholly or substantially of interconnected groups of islands. Their legal regime is principally contained in Part IV of UNCLOS, Articles 46–54.

The foundation of the regime is the archipelagic baseline under Article 47. A qualifying archipelagic State may draw straight baselines around the outermost islands and drying reefs of the archipelago, subject to important restrictions including the 1:1 to 9:1 water-to-land ratio, the general 100 nautical mile baseline limit and the limited 125 nautical mile exception.

Under Article 49, the archipelagic State exercises sovereignty over the waters enclosed by those baselines, together with the airspace above and the seabed and subsoil. However, this sovereignty is qualified by important rights of other States.

The two most important passage regimes are:

Article 52 → Innocent Passage

and

Article 53 → Archipelagic Sea Lanes Passage

Archipelagic sea lanes passage is particularly important because it protects the passage of both ships and aircraft through the archipelago. Submarines exercising this form of passage may navigate in their normal submerged mode.

The central legal balance is therefore:

Archipelagic-State Sovereignty + International Navigation Rights

The most important distinction to remember is:

Archipelagic Waters → Sovereignty

EEZ → Sovereign Rights

High Seas → No State Sovereignty

For examination purposes, the topic can be reduced to:

47 – 49 – 52 – 53

47 → Baselines

49 → Sovereignty

52 → Innocent Passage

53 → Archipelagic Sea Lanes Passage

and:

1:9 – 100 – 125

Water-land ratio – Baseline length – Exceptional baseline length