Each certifying agency have their own recomendations of when a scuba diver should refresh their skills. Yet, it is left to each individual dive centre to set their own rules based on the divers experience and how long since their last dive.
A good rule of thumb is if you have not dived for 6 months or longer and are not very experienced then expect to have to do one of the refresher courses before being allowed to dive again.
Koh Tao is renowned as a perfect place for scuba dive training. Furthermore, it offers a wonderful variety of dive sites for the certified scuba diver regardless of their experience. Spectacular submerged pinnacles poke like mountain tops from the sea floor, colourful coral gardens and large boulder formations teeming with tropical reef fish await you on your fun dives. Rocky substrate and flat sandy bottoms conceal many strange oddities such as pipefish, various sea slugs and the occasional sea horse for the sharp eyed scuba diver to find. The abundance of marine life from large pelagic ocean wanderers to minute crustaceans caters for all divers needs.
Sail Rock is regarded as one of the best dive sites the gulf of Thailanhas to offer. It is a gigantic rock formation that rises from the sea bed, up to and above the surface. As it is the only formation for miles around it attracts a lot of small aquatic life which in turn attracts the bigger stuff. You will be greeted by an abundance of tropical reef fish, hard and soft corals and plenty of bigger fish such as chevron barracuda, giant groupers and various types of trevally. It is often visited by whale sharks and is the seasonal home to other shark species besides.