The Outer Islands or Coralline Seychelles is a collective term for those islands of the Seychelles that are not on the shallow Seychelles Bank (Seychelles Plateau) which defines the location of the Inner Islands. They are located at distances of 230 to 1150 km from the main Seychelles island of Mahé, and are all of coral formation. The local name for the islands is Zil Elwannyen Sesel. The islands are outside the administrative and electoral Districts of Seychelles.
The coral islands are flat with elevated coral reefs at different stages of formation. They are generally low-lying, and often form atolls around a central lagoon. The soils of the corraline Seychelles are generally sandy and infertile, and hold little fresh water. The lack of natural fresh water sources and infertile soils of these islands can sustain human life only with difficulty.
The Granitic Seychelles, by contrast, are composed of granite, and are ancient fragments of continental crust. They are generally more mountainous and humid.
The Outer Islands are divided into five groups:
The Outer Islands comprise 211.3 km² (46% of the total land area of the Seychelles), but less than 2% of the population of the Seychelles. Eleven islands are inhabited, with the largest settlement on Coëtivy Island.