Geography
The entire land area of the islands is a mere 63.17 km², with the largest island, Diego Garcia, having an area of 27.20 km². The total area, including lagoons within atolls, however, is more than 15,000 km², of which 12,642 km² are accounted by the Great Chagos Bank, the second largest atoll structure of the world (after the completely submerged Saya de Malha Bank). The shelf area is 20,607 km², and the Exclusive Economic Zone, which borders the corresponding zone of the Maldive Islands in the north, has an area of 639,611 km² (including territorial waters).
The largest individual islands are Diego Garcia (27.20 km²), Eagle (Great Chagos Bank, 2.45 km²), Île Pierre (Peros Banhos, 1.50 km²), Eastern Egmont (Egmont Islands, 1.50 km²), Île du Coin (Peros Banhos, 1.28 km²) and Île Boddam (Salomon Islands, 1.08 km²).
The number of atolls in the Chagos Archipelago is given as four or five in most sources, plus two island groups and two single islands, mainly because it is not recognized that the Great Chagos Bank is a huge atoll structure (including those two island groups and two single islands), and because it is not recognisd that Blenheim Reef has islets or cays above or just reaching the high water mark.
In addition to the seven atolls with dry land reaching at least the high water mark, there are nine reefs and banks, most of which can be considered permanently submerged atoll structures. They are listed in the table from north to south:
| Atoll/Reef/Bank (alternate name) |
type | Area (km²) | number of islands |
Location | ||||
|---|---|---|---|---|---|---|---|---|
| Land | Total | |||||||
| 0 | unnamed bank | submerged bank | – | 3 | – | 04°25′S 72°36′E / 4.417°S 72.6°E / -4.417; 72.6 | ||
| 1 | Colvocoresses Reef | submerged atoll | – | 10 | – | 04°54′S 72°37′E / 4.9°S 72.617°E / -4.9; 72.617 (Colvocoresses Reef) | ||
| 2 | Speakers Bank | unvegetated atoll | >0 | 582 | 1) | 04°55′S 72°20′E / 4.917°S 72.333°E / -4.917; 72.333 (Speakers Bank) | ||
| 3 | Blenheim Reef (Baixo Predassa) | unvegetated atoll | 0.02 | 37 | 4 | 05°12′S 72°28′E / 5.2°S 72.467°E / -5.2; 72.467 (Blenheim Reef) | ||
| 4 | Benares Shoals | submerged reef | – | 2 | 05°15′S 71°40′E / 5.25°S 71.667°E / -5.25; 71.667 (Benares Shoals) | |||
| 5 | Peros Banhos | atoll | 13 | 503 | 32 | 05°20′S 71°51′E / 5.333°S 71.85°E / -5.333; 71.85 (Peros Banhos) | ||
| 6 | Salomon Islands | atoll | 5 | 36 | 11 | 05°22′S 72°13′E / 5.367°S 72.217°E / -5.367; 72.217 (Salomon Islands) | ||
| 7 | Victory Bank | submerged atoll | – | 21 | – | 05°32′S 72°14′E / 5.533°S 72.233°E / -5.533; 72.233 (Victory Bank) | ||
| 8a | Nelsons Island | parts of mega-atoll Great Chagos Bank |
0.81 | 12642 | 1 | 05°40′53″S 72°18′39″E / 5.68139°S 72.31083°E / -5.68139; 72.31083 (Nelson Island) | ||
| 8b | Three Brothers (Trois Frères) | 0.37 | 3 | 06°09′S 71°31′E / 6.15°S 71.517°E / -6.15; 71.517 (Three Brothers) | ||||
| 8c | Eagle Islands | 2.63 | 2 | 06°12′S 71°19′E / 6.2°S 71.317°E / -6.2; 71.317 (Eagle Islands) | ||||
| 8d | Danger Island | 0.66 | 1 | 06°23′00″S 71°14′20″E / 6.3833333°S 71.23889°E / -6.3833333; 71.23889 (Danger Island) | ||||
| 9 | Egmont Islands | atoll | 4 | 29 | 7 | 6°40′S 71°21′E / 6.667°S 71.35°E / -6.667; 71.35 (Egmont Islands) | ||
| 10 | Cauvin Bank | submerged atoll | – | 12 | – | 06°46′S 72°22′E / 6.767°S 72.367°E / -6.767; 72.367 (Cauvin Bank) | ||
| 11 | Owen Bank | submerged bank | – | 4 | – | 06°48′S 70°14′E / 6.8°S 70.233°E / -6.8; 70.233 (Owen Bank) | ||
| 12 | Pitt Bank | submerged atoll | – | 1317 | – | 07°04′S 72°31′E / 7.067°S 72.517°E / -7.067; 72.517 (Pitt Bank) | ||
| 13 | Diego Garcia | atoll | 30 | 174 | 42) | 07°19′S 72°25′E / 7.317°S 72.417°E / -7.317; 72.417 (Diego Garcia) | ||
| 14 | Ganges Bank | submerged atoll | – | 30 | – | 07°23′S 70°58′E / 7.383°S 70.967°E / -7.383; 70.967 (Ganges Bank) | ||
| 15 | Wight Bank | 3 | 07°25′S 71°31′E / 7.417°S 71.517°E / -7.417; 71.517 (Wight Bank) | |||||
| 16 | Centurion Bank | 25 | 07°39′S 70°50′E / 7.65°S 70.833°E / -7.65; 70.833 (Centurion Bank) | |||||
| Chagos Archipelago | Archipelago | 63.17 | 15427 | 64 | 04°54' to 07°39'S 70°14' to 72°37' E |
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| 1) a number of drying sand cays | ||||||||
| 2) main island and three islets at the northern end | ||||||||
The deep oceanic waters around the Chagos Islands, out to the 200 nautical mile limit, include an exceptional diversity of undersea geological features (such as 6000m deep trenches, oceanic ridges, and sea mounts). These areas almost certainly harbour many undiscovered and specially adapted species. Although the deepwater habitats surrounding the islands have not been explored or mapped in any detail, work elsewhere in the world has shown that high physical diversity of the sea floor is closely linked to a high diversity of species.
Read more about this topic: Chagos Archipelago
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