In fact, in terms of both marine life and bottom topography, there's more variety than you'll find in most other dive destinations around the world. The Similan Islands has almost everything - coral walls (if we count Koh Bon, to the north, as one of the Similans), big rocks, huge sea fans and barrel sponges, caves, swim-throughs, and plenty of shallows for snorkelling as well. For, although the fringing waters around the islands average from 30-45m dropping down to 70-80m between islands, you'll find coral gardens in as little as six to seven metres.