| Group | Type | Key Islands | Features |
|---|---|---|---|
| Inner Islands | Granitic (continental fragments) | Mahé, Praslin, La Digue, Silhouette | Mountains, rainforest, endemic species, most population |
| Outer Islands | Coralline (atolls, reef islands, sand cays) | Amirantes, Farquhar, Aldabra, Cosmoledo | Low-lying, lagoons, seabird colonies, marine reserves |