The Seychelles is an archipelago in the Indian Ocean, northeast of Madagascar, consisting of more than 100 islands of which 83 are named and 46 are permanently uninhabited. Mahé is the principal island comprising of 142 sq km, with the islands of Praslin, La Digue and Silhouette being the next important . Situated about 1,600 km off the east coast of Africa, Mahe extends 27 km north to south and 11 km east to west and has a coastline of 127 km.
The Seychelles Islands are the highest point of the Mascarene Ridge, an Indian Ocean ridge running in a generally north-south direction.
The granite islands rise above the sea surface to form a peak or ridge which, in the case of Mahé, attains an elevation of 3,000 ft at Morne Seychellois, the highest point. Rugged crests, towering cliffs, boulders and domes contribute to the islands great natural beauty. Here and there, in the hollows between the rock relief, are pockets of lateritic soil, often very thin and easily eroded.
Mahé possesses white sandy beaches which are flats of coral and shell known locally as plateaus, although they rarely achieve an elevation of more than 10 ft above sea level. Small streams descending the mountain slopes deposit alluvial material, creating the most fertile soils on the island.
The coralline Seychelles are, in contrast, low-lying, rising only a few feet above the surface of the sea. Many have the typical Indian Ocean lagoon. Soils tend to be thin with poor moisture retention. These island are suited only to coconut palm and a few other species.