Seychelles Geography & Climate

The Seychelles is scattered across more than 1.3 million square kilometres of the western Indian Ocean, around 1,600 kilometres east of the African mainland, with a total land area of only about 455 square kilometres. It divides into two groups that have almost nothing in common geologically.

The inner islands are granite

Mahé, Praslin, La Digue, Silhouette and their neighbours are made of granite between 650 and 750 million years old — fragments of Gondwana left behind when India separated from Africa and Madagascar. This makes them close to unique: almost every other island in the open ocean is volcanic or coral. The rock weathers into the huge rounded boulders that define the beaches, and Mahé rises steeply to 905 metres at Morne Seychellois.

The outer islands are coral

The Amirantes, Alphonse, Farquhar and Aldabra groups are low coralline atolls and sand cays, mostly uninhabited, some more than a thousand kilometres from the capital. Aldabra is the second-largest raised coral atoll in the world, with a central lagoon that empties and refills with the tide.

Reef, shelf and deep water

The inner islands sit on the shallow Seychelles Bank, which is why the water inshore is turquoise and calm; beyond its edge the sea drops to abyssal depths. The reefs suffered severe bleaching in 1998 and again in 2016.

Outside the cyclone belt

The main islands lie close enough to the equator to sit outside the usual cyclone track, which is unusual for the Indian Ocean and is why the beaches and the trees look the way they do.

The Seychelles sits between four and ten degrees south of the equator, and its climate is correspondingly even: temperatures stay between roughly 24 and 32°C throughout the year, and no month is genuinely cool.

Two monsoons

The north-west monsoon, from December to March, is hotter and more humid, with heavy rain that usually falls in short bursts rather than all day, and light winds. The south-east trades, from May to September, are drier, breezier and a little cooler, and they bring choppier seas on exposed coasts.

The changeover months

April and October sit between the two systems, when the wind drops almost entirely. The water goes glassy, underwater visibility reaches its annual peak, and these are the months divers book a year ahead for.

Rain, and where

Mahé catches far more rain than the low outer islands — over two metres a year on the mountains, against well under a metre on Aldabra — because its height forces the moist air upward. The mountain interior can be wet while the coast a few kilometres away stays dry.

Cyclones, and their absence

The inner islands lie close enough to the equator that cyclones almost never form over them, which is why the vegetation and the beaches are undamaged in a way that Mauritius and Madagascar’s are not. The southern outer islands are closer to the belt and do get hit.

Seaweed and seasons on the beach

During the south-east trades, seaweed accumulates on south- and east-facing beaches and hotels rake it daily. If a particular beach matters to you, check which way it faces against the season.