Scuba diving in Thailand takes place both off the east coast in the Gulf of Thailand and off the west coast in the Andaman Sea. While the Andaman Sea is considered the best diving in the country, it is generally more expensive than the east cost and in our opinion is a better place to dive recreationally, or to work after you’ve become a professional. For your divemaster internship and IDC I recommend the east coast, specifically Koh Tao.
Diving in Thailand is split into two seasons, one for each coast. October to April is the best time for diving in the Andaman Sea on the west coast, the water is at it’s clearest and the average surface temperature is 28 degrees Celsius (82.4 Fahrenheit). Plus between March and April giant manta rays come to the Similan Islands, making it a prime dive spot. During May to September the west coast experiences heavy rainfall and one is better off diving in the Gulf of Thailand, with the best diving being around Koh Tao.
Two of my favourite spots to dive in the Gulf of Thailand are Chumpon Pinnacle, located 11km off of Koh Tao and Sail Rock, which is situated between Koh Tao and Koh Pha Ngan.
Chumpon Pinnacle is one of Koh Tao’s best dive sites and is suited for advanced open water divers and up with the depth of site ranging from 14 – 35m. It consists of a large main pinnacle that is surrounded by several smaller ones. These pinnacles have multiple plateaus that are blanketed with branch corals, barrel whips and sea sponges, they are also frequented by schools of chevron barracuda. Chumpon Pinnacle is also the best dive site to spot whale sharks in the Gulf of Thailand (with the best months being March, April, May, September and October).
Sail Rock is at first unassuming, but once you enter the water you’re quickly surrounded by chevron barracuda, schools of trevally, jacks and mackerel. There’s also the possibility of encountering whale sharks depending on the season and manta rays. One of Sail Rock’s most famous features is its natural chimney that you can enter at 6m and drop down through it to exit at 18m!