Astove lies 1056km from Mahé and approximately 185km ESE of Aldabra (10 04' S, 47 44' E). Astove is a raised coral island with a substantial shallow lagoon (approximately 4.5 x 2 kilometres) opening to the sea through a single narrow channel on the south coast. The exposed eastern side of the island is dominated by low scrub and mangroves on the lagoon side, while the western side is quite highly vegetated.
On the western side there is an abandoned copra plantation and an apparently healthy population of giant tortoises. Astove is no longer inhabited but it was once exploited for guano mining, and more recently for the production of cotton, sisal, maize and copra.
There is an abandoned settlement on the western coast and a grass airstrip on the north east point of the island.
Astove has a gently shelving rocky coastline to the east, an undercut coastline on the southwestern coast and a 3km long sand beach on the north west coast.
The shelf slopes gently out to sea on the east side of Astove, but there is a dramatic cliff on the west side that drops sheer to about 100m and continues to drop steeply to over 2000m.
The cliff starts directly at the end of the 300m wide tidal flat from barely 6m deep and has many caves.