Maritime Boundary Definitions

Find out more about New Zealand's maritime zones and boundaries.

 

New Zealand's maritime zones

On 19 July 1996, New Zealand ratified the United Nations Convention on the Law of the Sea (UNCLOS). Under UNCLOS there are a number of maritime zones defined generally by their distance from the land, but more precisely, as their distance from the Territorial Sea Baseline (TSB).

 Territorial sea (TS), Contiguous Zone (CZ) and Exclusive Economic Zone (EEZ)
Zones of significance: Territorial sea (TS), Contiguous Zone (CZ) and Exclusive Economic Zone (EEZ)
 

New Zealand's maritime zones are:

 

Definition of Territorial Sea Baseline (TSB)

The term Territorial Sea Baseline refers to the line from which the seaward limits of New Zealand's maritime zones are measured. The breadth of the territorial sea, the seaward limits of the contiguous zone, the exclusive economic zone and, in some cases, the continental shelf, are measured from the Territorial Sea Baseline.

References: TERRITORIAL SEA [CONTIGUOUS ZONE] AND EXCLUSIVE ECONOMIC ZONE ACT 1977 Sections 5 and 6

5. Baseline of territorial sea

i. Except as otherwise provided in section 6 [or section 6A] of this Act, the baseline from which the breadth of the territorial sea of New Zealand is measured shall be the low-water mark along the coast of New Zealand, including the coast of all islands.

ii. For the purposes of this section, a low-tide elevation that lies wholly or partly within the breadth of sea that would be territorial sea if all low-tide elevations were disregarded for the purpose of the measurement of the breadth of the territorial sea shall be treated as an island.

6. Baseline of territorial sea adjacent to bay

In the case of the sea adjacent to a bay, the baseline from which the breadth of the territorial sea is measured

i. Where the bay has only one mouth and the distance between the low-water marks of the natural entrance points of the bay does not exceed 24 nautical miles, shall be a straight line joining those low-water marks; and

ii. Where, because of the presence of islands, the bay has more than one mouth and the distances between the low-water marks of the natural entrance points of each mouth added together do not exceed 24 nautical miles, shall be a series of straight lines across each of the mouths so as to join those low-water marks; and

iii. Where neither paragraph (a) nor paragraph (b) of this section applies, shall be a straight line 24 nautical miles in length drawn from low-water mark to low-water mark within the bay in such a manner as to enclose the maximum area of water that is possible with a line of that length.

6A Straight baselines

(1) Subject to section 6 of this Act, in the following circumstances the method of drawing straight lines joining points may be employed in drawing the baseline from which the breadth of the territorial sea is measured:

i. Where a river flows directly into the sea:

ii. Where the coast is highly unstable because of the presence of a delta or other natural conditions:

iii. Where the coast is deeply indented:

iv. Where there is a fringe of islands along the coast in its immediate vicinity.

(2) For the purposes of subsection (1) of this section, the points between which straight lines may be drawn are,-

i. In a case where a river flows directly into the sea, a point at each side of the river's mouth on the low-water line of the river's banks:

ii. In a case where the coast is highly unstable because of the presence of a delta or other natural conditions, points along the furtherest seaward extent of the low-water line:

iii. In any other case, points that are appropriate in the circumstances.

(3) Where it is necessary to determine the points between which straight lines may be drawn for the purposes of paragraph (b) or paragraph (c) of subsection (2) of this section,-

A. The following rules shall be observed:

i. Straight baselines shall not depart to any appreciable extent from the general direction of the coast:

ii. Sea areas lying within straight baselines shall be sufficiently closely linked to the land of New Zealand to be internal waters of New Zealand:

iii. Straight baselines shall be drawn to and from low-tide elevations only where lighthouses or similar installations, which are permanently above sea level, have been built on the low-tide elevations or where the drawing of baselines to and from such elevations has received general international recognition.

B. Economic interests peculiar to the region concerned, the reality and the importance of which are clearly evidenced by long usage, may be taken into account.

(4) Where, in a case where the coast is highly unstable because of the presence of a delta or other natural conditions, a straight line has been drawn pursuant to this section, that line remains the baseline, notwithstanding any subsequent regression of the low-water line, until it is changed in accordance with this Act.

(Cf United Nations Convention on the Law of the Sea, articles 7 and 9)

The territorial sea baseline may be of various types depending upon the shape of the coastline in any given locality:

  • The Normal baseline corresponds with the low-water line (attachment below) along the coast, including the coasts of islands. Under certain provisions set out in the Convention, a normal baseline can be drawn around low-tide elevations. Low-Tide Elevations are defined as naturally formed areas of land surrounded by and above water at low tide but submerged at high tide. For New Zealand purposes, the normal baseline corresponds to the level of Chart Datum which is in most cases an approximation of the Lowest Astronomical Tide1.
  • Straight baselines are a system of straight lines joining specified or discrete points on the low-water line, usually known as straight baseline (attachment below) end points, which may be used in localities where the coastline is deeply indented and cut into, or if there is a fringe of islands along the coast in its immediate vicinity.
  • Bay or river closing lines are straight lines drawn between the respective low-water marks of the natural entrance points of bays or rivers (attachment below). There are rules on how the bay may be closed off.
  • Archipelagic baselines are straight lines joining the outermost points of the outermost islands and drying reefs which may be used to enclose all or part of an archipelago forming all or part of an archipelagic State. This type of baseline is not applicable to New Zealand.
1 Lowest Astronomical Tide is the lowest level to which sea level can be predicted to fall under normal meteorological conditions.
 

Definition of Internal Waters (landward of the TSB)

The internal waters are all those areas of the sea that are on the inside of New Zealand including any areas of the sea that are on the landward side of the baseline of the territorial sea of New Zealand.

References: TERRITORIAL SEA [CONTIGUOUS ZONE] AND EXCLUSIVE ECONOMIC ZONE ACT 1977 Sections 4

4. Internal waters-

The internal waters of New Zealand include any areas of the sea that are on the landward side of the baseline of the territorial sea of New Zealand

 

Definition of Territorial Sea (12nm limit)

The Territorial Sea is an area of water not exceeding 12 nautical miles in width which is measured seaward from the territorial sea baseline.

References: TERRITORIAL SEA [CONTIGUOUS ZONE] AND EXCLUSIVE ECONOMIC ZONE ACT 1977 Sections 3

3. The territorial sea-

The territorial sea of New Zealand comprises those areas of the sea having, as their inner limits, the baseline described in sections 5 and 6 [and 6A] of this Act and, as their outer limits, a line measured seaward from that baseline, every point of which line is distant 12 nautical miles from the nearest point of the baseline

 

Definition of Contiguous Zone (24nm limit)

The Contiguous Zone is a belt of water adjacent to the territorial sea, the outer limits of which do not exceed 24 nautical miles from the territorial sea baseline.

References: TERRITORIAL SEA [CONTIGUOUS ZONE] AND EXCLUSIVE ECONOMIC ZONE ACT 1977 Sections 8A

8A.The contiguous zone-

(1) In this section, the term "marker" means the line that, pursuant to section 3 of this Act, marks the outer limits of the territorial sea of New Zealand.

(2) The contiguous zone of New Zealand comprises those areas of the sea having, as their inner limits, the marker, and, as their outer limits, a line measured seaward from the marker, every point of which line is distant 12 nautical miles from the nearest point of the marker.

(Cf United Nations Convention on the Law of the Sea, article 33)

 

Definition of Exclusive Economic Zone (200nm limit)

The Exclusive Economic Zone is an area of sea beyond and adjacent to the territorial sea. The outer limit of the exclusive economic zone cannot exceed 200 nautical miles from the territorial sea baseline. Where the New Zealand EEZ abuts the maritime zone of another nation, a median line between the nations is agreed.

References: TERRITORIAL SEA [CONTIGUOUS ZONE] AND EXCLUSIVE ECONOMIC ZONE ACT 1977 Sections 9

9.The exclusive economic zone-

(1) The exclusive economic zone of New Zealand comprises those areas of the sea, seabed, and subsoil that are beyond and adjacent to the territorial sea of New Zealand, having as their outer limits a line measured seaward from the baseline described in sections 5 and 6 [and 6A] of this Act, every point of which line is distant 200 nautical miles from the nearest point of the baseline.

(2) Notwithstanding subsection (1) of this section, where-

a. Any part of the median line between New Zealand and any other country is less than 200 nautical miles from the nearest part of the baseline of the territorial sea of New Zealand; and

b. No other outer limit of the exclusive economic zone is for the time being determined by an Order in Council made under subsection (3) or subsection (4) of this section- that part of the median line shall be an outer limit of the zone.

(3) The Governor-General may from time to time, by Order in Council, declare that any specified provisions of this Part of this Act, and any other specified provisions in this Act relating to the exclusive economic zone, shall apply to the Ross Dependency, with such modifications and exceptions (if any) as he may specify in the Order.

(4) For the purposes of implementing any international agreement, or the arbitral award of any international body, or the judgment of any international Court, or for any other purpose in accordance with international law, the Governor-General may from time to time, by Order in Council, declare that the exclusive economic zone shall not extend to any specified area of the sea, seabed, or subsoil, that would otherwise be included within the exclusive economic zone by virtue of this section.

 

Definition of Continental Shelf (CS)

The term "continental shelf" is generally taken to mean that part of the continental margin between the shoreline and the shelf break or, where there is no noticeable slope, between the shoreline and the point where the depth of the superjacent water is approximately between 100 and 200 metres.

In the UNCLOS article 76, the continental shelf of a coastal State comprises the submerged prolongation of the land territory of the coastal State - the seabed and subsoil of the submarine areas that extend beyond its territorial sea to the outer edge of the continental margin, or to a distance of 200 nautical miles where the outer edge of the continental margin does not extend up to that distance. The continental margin consists of the seabed and subsoil of the shelf, the slope and the rise. It does not include the deep ocean floor with its oceanic ridges or the subsoil thereof.

According to article 76, a coastal State may establish the outer limits of its juridical continental shelf wherever the continental margin extends beyond 200 nautical miles by establishing the foot of the continental slope, by meeting the requirements stated for the thickness of sedimentary rocks, by satisfying geomorphological requirements and by meeting distance and depth criteria, or by any combination of these methods (Article 76, paragraphs 4 - 7).

Read about the LINZ Continental Shelf Project

References: CONTINENTAL SHELF ACT 1964 Section 2

2. Interpretation-

(1) In this Act, unless the context otherwise requires,- ...

"Continental shelf" means the seabed and subsoil of those submarine areas that extend beyond the territorial limits of New Zealand, throughout the natural prolongation of the land territory of New Zealand, to the outer edge of the continental margin, or to a distance of 200 nautical miles from the baselines from which the breadth of the territorial sea is measured (as described in sections 5 and 6 [and 6A] of the Territorial Sea and Exclusive Economic Zone Act 1977) where the outer edge of the continental margin does not extend to that distance:]

The Continental margin is defined in Article 76 of the United Nations Convention on the Law of the Sea (UNCLOS).

 

Definition of a Nautical Mile

A nautical mile is a unit of distance equal to 1,852 metres (Section 2 of the TS, EEZ Act 1977).

This value was adopted by the International Hydrographic Conference in 1929 and has subsequently been adopted by the International Bureau of Weights and Measures.

The length of the nautical mile is very close to the mean value of the length of 1 minute of latitude, which varies from approximately 1,843 metres at the equator to 1,861.6 metres at the pole.