Maldives
The Maldives Islands form a linear chain of
highly distinctive and unusual atoll formations located in the eastern Arabian Sea region of the Indian
Ocean, situated 440 km southwards from the Lakshadweep Islands and 450 km
northwards from the Chagos Archipelago; Cape Comorin on the Indian coast lies
480 km to the northeast. In all, there are 23 atolls and 3 solitary islands that comprise this isolated
nation. Strictly speaking, in oceanographic terms, the Maldives actually comprises 16 atolls, 5 oceanic
faros and 4 oceanic platform reefs. In total, there are assumed to be 1,192 islands and islets with a
combined land area estimated to be in the region of 300 km².
The Maldivian archipelago comprises a 860 km long, north-south orientated, chain of atolls forming a single chain that opens in the centre to form a double-chain of up to 130 km in width. The atolls found here are among the largest found on earth: with Thiladhunmathee-Miladhunmadulu (3,680 km²) and Huvadhoo (3,200 km²) being the worlds largest and second largest, respectively. They are only eclipsed in overall size by the 13,000 km² and largely submerged (and thus, not a true atoll) Great Chagos Bank. Note that Kwajalein in the Marshall Islands is often erroneously quoted as being the world's largest atoll. Also note that here "largest" refers to total surface area and not to land area — in this regard, the Maldivian atolls would rank as extremely small.
The atolls found in the Maldives
are generally unlike either those within the Pacific Ocean, or those occurring elsewhere in the Indian Ocean. In
the northern reaches of the archipelago atolls form large elongate bank structures that have rims lined with
a highly discontinuous series of reefs. Each reef itself (see image at left) usually harbours a central lagoon
and may contain one or more islands — in stark contrast to the long linear reef rims of Pacific atolls
that contain no lagoons and that are topped by long strips of land known as motu. Towards the south,
the nature of the atolls becomes more "Pacific-like" in that reef rims are more continuous. Lagoons also exhibit
a north to south difference: those in the north often contain a profusion of faros reefs, coral knolls
and patch reefs.
The atolls are the central members of an extensive submarine feature known as the the Chagos-Laccadive Plateau. Their exact method of formation is, at present, not fully understood.
The islands, reefs and lagoons cover an area of around
21,000 km², with some 4,500 km² of reefs. Of these reefs, 538 are rim and oceanic reefs, covering 3,700
km² and 1,500 are patch reefs occurring within the lagoons, covering 791.92 km². Islands are, on average,
very small — the vast majority being less the 0.5 km² in area. The largest islands include: Gan (5.166
km²) on Hadhdhunmathee atoll, Hithadhoo (4.673 km²) on Addu atoll, Fuvah Mulah (4.2 km²), Isdhoo
(2.937 km²) on Hadhdhunmathee atoll, Kaashidhoo (2.765 km²), Gan on Addu atoll (2.649 km²), Gan
on Huvadhoo atoll (2.636 km²), Hanimaadhoo (2.595 km²) on Thiladhunmathee-Miladhunmadulu atoll, Baarah
(2.488 km²) on Thiladhunmathee-Miladhunmadulu atoll and Filladhoo (2.256 km²) also on
Thiladhunmathee-Miladhunmadulu atoll.
Islands are of extremely low elevation — generally less than 2 m above sea level — and are composed from a mixture of coral fragments and skeletal remains of small marine organisms. The resulting sandy soil is nutrient-poor and highly alkaline. Freshwater is found in shallow lenses, 1 m to 3 m below the surface. These factors give the islands a vegetation cover consisting mainly of low-lying, salt-tolerant shrubs. Taller stands of native tropical-type trees are rare — most of the original flora of the islands has been replaced with cultivated species such as Coconut Palm and Breadfruit.
The climate is tropical and monsoonal, with a dry season (November to April) and a wet season (May to October). The southwest monsoon sees the arrival of heavy rain and sometimes very windy weather, while the northeast monsoon is dry and calm. Rainfall is at it highest in the south, where 1,924 mm may fall; the north is slightly drier with an annual rainfall of 1,786 mm. The location of the Maldives near the equator and at sea level means that there is very little temperature variation throughout the year: annual average daily maximums of 30.4 °C and average daily minimums of 25.9 °C are typical.