The archipelago consists of 115 islands and thirty prominent rock formations scattered throughout a self-proclaimed exclusive economic zone (EEZ) of more than 1.35 million square kilometers of ocean. Some forty islands are granitic and lie in a ninety-kilometer radius from Mahé, the main island. The remaining islands are coralline, stretching over a 1,200-kilometer radius from Île aux Vaches in the northeast to the Aldabra Atoll in the southwest. The islands are all small-- the aggregate land area is only 444 square kilometers, about twoand -a-half times the size of Washington, D.C.
Mahé is twenty-five kilometers long and no more than eight kilometers wide. It contains the capital and only city, Victoria, an excellent port. Victoria lies approximately 1,600 kilometers east of Mombasa, Kenya; 2,800 kilometers southwest of Bombay; 1,700 kilometers north of Mauritius; and 920 kilometers northeast of Madagascar. The only other important islands by virtue of their size and population are Praslin and La Digue, situated about thirty kilometers to the northeast of Mahé.
The granitic islands are the peaks of the submarine Mascarene Plateau, a continental formation theorized to be either a part of Africa separated when Asia began to drift away from the original single continent of Gondwanaland, or the remnants of a microcontinent that existed up to the beginning of the Tertiary Period, approximately 50 million years ago. The granitic islands are characterized by boulder-covered hills and mountains as high as 940 meters rising abruptly from the sea. Elsewhere, narrow coastal plains extend to the base of the foothills. Extensively developed coral reefs are found mainly on the east coasts because of the southwest trade winds and equatorial current. Ninety-nine percent of the population is located on the granitic islands, and most are on Mahé.
The coralline islands differ sharply from the granitic in that they are very flat, often rising only a few feet above sea level. They have no fresh water, and very few have a resident population. Many, like Île aux Vaches, Île Denis, the Amirante Isles, Platte Island, and Coetivy Island are sand cays upon which extensive coconut plantations have been established. Some of the coralline islands consist of uplifted reefs and atolls covered with stunted vegetation. Several of these islands have been important breeding grounds for turtles and birds, as well as the sites of extensive guano deposits, which formerly constituted an important element of the Seychellois economy but now for the most part are depleted. Aldabra Islands, the largest coralline atoll with an area greater than Mahé, is a sanctuary for rare animals and birds.
The uniqueness of the Seychelles' ecology is reflected in the US$1.8 million project of the Global Environment Trust Fund of the World Bank entitled Biodiversity Conservation and Marine Pollution Abatement, that began in 1993. The World Bank study for this project states that the islands contain, out of a total of 1,170 flowering plants, "at least seventy-five species of flowering plants, fifteen of birds, three of mammals, thirty of reptiles and amphibians, and several hundred species of snails, insects, spiders and other invertebrates" found nowhere else. In addition, the waters contain more than 900 kinds of fish, of which more than one-third are associated with coral reefs. Specific examples of unique birds are the black paradise flycatcher, the black parrot, the brush warbler, and a flightless rail.
As a result of extensive shipping to Seychelles that brings needed imports and the discharge of commercial tuna fishing, the waters are becoming polluted. Furthermore, goats brought to Aldabra Islands are destroying much of the vegetation on which giant turtles, including two species unique to Seychelles--the green and the hawksbill--feed or seek shade.
Seychelles began addressing the conservation problem in the late 1960s by creating the Nature Conservancy Commission, later renamed the Seychelles National Environment Commission. A system of national parks and animal preserves covering 42 percent of the land area and about 26,000 hectares of the surrounding water areas has been set aside. Legislation protects wildlife and bans various destructive practices. In Seychelles' 1990-94 National Development Plan, an effort was made to include in the appropriate economic sectors of the development plan environment and natural resources management aspects.
Also connected with ecology is a World Bank project dealing with the environment and transportation. Launched in 1993 with a loan of US$4.5 million, it is designed to improve the infrastructure of Seychelles with regard to roads and airports or airstrips so as to encourage tourism as a source of income, while simultaneously supporting environmental programs in resource management, conservation, and the elimination of pollution.
The climate of Seychelles is tropical, having little seasonal variation. Temperatures on Mahé rarely rise above 29 C. or drop below 24 C. Humidity is high, but its enervating effect is usually ameliorated by prevailing winds. The southeast monsoon from late May to September brings cooler weather, and the northwest monsoon from March to May, warmer weather. High winds are rare inasmuch as most islands lie outside the Indian Ocean cyclone belt; Mahé suffered the only such storm in its recorded history in 1862. Mean annual rainfall in Mahé averages 2,880 millimeters at sea level and as high as 3,550 millimeters on the mountain slopes. Precipitation is somewhat less on the other islands, averaging as low as 500 millimeters per year on the southernmost coral islands. Because catchment provides most sources of water in Seychelles, yearly variations in rainfall or even brief periods of drought can produce water shortages. Small dams have been built on Mahé since 1969 in an effort to guarantee a reliable water supply, but drought can still be a problem on Mahé and particularly on La Digue.