Crystal Dive — Koh Tao SSI Diamond Instructor Training Centre

Crystal Dive is one of Koh Tao's longest-running schools, operating from a beachfront resort at Mae Haad for over 25 years. It is an SSI Diamond Instructor Training Centre and lists more than 45 SSI programmes, from Basic Diver and Open Water through specialties such as Deep, Wreck, Nitrox, Sidemount, Independent Diving and Photo & Video, up to Divemaster, Instructor and Assistant Instructor Trainer level. Kids' courses are also offered.

The centre runs two custom-built dive boats, has two swimming pools and air-conditioned classrooms, and discounts on-site accommodation for guests on courses. A strong eco strand runs through the programme, with marine ecology specialties (shark, turtle, nudibranch and coral identification), coral restoration work and conservation internships. Fun-dive trips go out twice daily to sites such as Sail Rock, Twins, White Rock and the HTMS Sattakut wreck, with Nitrox available for certified divers.

At the time of writing, fun dives were priced from 2,200 THB for a two-dive trip up to 9,000 THB for a ten-dive package, including standard equipment, dive computer rental and 30-day dive insurance.