Entry Fee : PADI course: THB 8,500,
SSI course: THB 7,500
Koh Tao has some of the best and cheapest diving spots in all of Thailand. Due to immense competition, there are over 50 diving shops in Koh Tao to choose from. The dive courses are cheap and there are abundant options.
If you want to do a full course, the two main training systems are PADI or SSI system. Both have their own teaching methods, but both the certifications have hardly any difference. A few good diving schools are New Way, Scuba Junction, Simple Life.