Classic dive sites such as the Similan Islands, Richelieu Rock and the Surin Islands can be visited by boat from Sub Aqua Dive Centre in Khao Lok, Thailand.
Three, five and eight-day trips cost from 255, 400 and 605 euros respectively and include two dives daily, lunch and hotel shuttles. The Nam Sai is the 25m vessel that serves these sites, and nitrox is available on board at no extra cost.