They are geographically part of the Comoro Islands between the French overseas region of Mayotte and the nation of Madagascar.

The climate is tropical and the terrain is low and flat, varying in height from sea level to 12 metres (39 ft).

Île de Lys in particular is a nesting ground for migratory seabirds, and turtles lay eggs on the beaches.

Historically flora on the islands mostly consisted of bois de rose, portia, banyan and other large native trees, many of which were felled following the establishment of the French settlement and plantation.

The islands are today nature reserves with a meteorological station garrisoned by the French Foreign Legion.