New Heaven Dive School

New Heaven is the dive school that made Koh Tao a conservation destination as well as a certification one. From its base in Chalok Baan Kao on the island's quieter south coast, it runs a marine conservation program that has become internationally known — reef restoration, artificial reef building, ecological monitoring and marine-resource courses that attract students who come specifically to work on the reef, not just look at it. The regular dive school runs alongside, with PADI courses at all levels, fun diving, and teaching that carries the house obsession with buoyancy and low-impact technique.

For travelers, the combination is unique. Do an Open Water course, then bolt on a conservation week and leave able to identify what you saw and having planted some of it. Chalok's bay-view calm suits that crowd — the south coast runs mellower than Sairee in every way.