Diving is one of the most absorbing tourist attractions in Thailand. If you go to Phuket holidays during the high season (November-April) the sea will be calm, the water turquoise and transparent, the days sunny, and you can expect perfect diving conditions. There are a lot of diving sites around or near Phuket with the entire new world to see and discover.
Beginners will find a company offering courses easily; there are a lot of them on the entire island. I mention only one of them, Sea World Dive Team (probably renamed to All 4 Diving) near hotel Patong, because they have the deepest pool which allows beginners to learn how to move vertically under the water before going to the open ocean yet.
During the high season one day diving trips start every day from almost all of the towns and ports at the west bank, from Patong Beach, Kamala, Kata, Karon, Rawai, Chalong, Bang Tao, or Surin. Longer travels to Phi Phi, Similans, or Mergui Archipelago are also very popular. You can go even to so called underwater safari to Burma, Malaysia, Indonesia, even to Bali. Prices of these journeys are very variable depending how long is the travel, if it is high season or it isn’t, and of course depending on the class of the rented cabin and a boat. Usually you have 2 to 3 dives daily during safari.
The biggest attraction is coral reef, but also shoals of fishes, rays, sharks. Sharks do not attack humans in this part of the world. Usually don’t. Pay attention to underwater snakes and jelly fishes. Some species of fishes are dangerous. Death accidents occur extremely rarely but they do. Diving is an extreme sport.
Diving schools organize courses in full scope, from PADI certificate to specialty and master courses including. You can become a specialist of deep diving, wracks explorer or film making.
In all, it’s a great drive in a beautiful part of Thailand.