The Seychelles Outer Islands are not a single beach holiday destination so much as a network of expedition-style coral islands reached by charter or resort-arranged flights from Mahe. For divers and snorkelers, the big draw is variety: Alphonse gives you polished lodge logistics, reef mantas, sailfish snorkeling, and over 20 snorkel sites; Desroches blends luxury with easy reef access, bike exploration, and dramatic topography; Astove and Cosmoledo push farther into wild-water territory with walls, sharks, turtles, and almost no visual noise from development. Conditions are best for mixed water trips in the calmer transition months of April-May and October-November, while June-September is windier and rougher. Go here when you want remoteness, healthy reef systems, and a trip that feels earned rather than convenient.