Koh Samui and its sister islands of Koh Tao and Koh Panghan are a diver's paradise. The exceptional diversity of the marine life, along with the warmth and stillness of the clear turquoise waters, has prompted many professional divers to praise the region as hosting the best dive sites in the world.

Within the Gulf of Thailand lies the Ang Thong National Marine Park, a group of islands offering a truly unique diving, swimming or snorkelling environment. The many small, mostly uninhabited islands, are ringed by rich soft and hard coral reefs, home to local flora and fauna. The shores are populated by the local long-tailed monkey, otters, tortoises, sea turtles and more, and the deserted white sand beaches are perfect for a pause for lunch.

The seas themselves are rich in both fish and mammals, and offer a fascinating insight into the complex ecosystem of the Thai oceans. You will see immense shoals of brightly-coloured angelfish and butterflyfish, as well as sea turtles, whale sharks, manta rays and barracudas. The amazing underwater rock formations provide a particularly varied caving and tunnelling adventure for the more experienced diver. There are many shallow water areas with lots of interest for the beginner diver, including many sea urchins, seahorses, anenomes and so on, with sufficient variety of Indo-Asian flora and fauna for advanced and well-travelled divers.

There are many diving shops throughout the Gulf of Thailand offering group outings, custom trips by speedboat and diving courses with official accreditation from beginners through to highly advanced and specialist certificates for rescue, safety, recovery, photography and more.

For those looking to enjoy the wonderful underwater views but without quite as much commitment as professional diving schools provide, then there's always the snorkel option. Choose your shallow water site, of which there are plenty, slip on your snorkel and dip down into the underwater jungle.

Of further interest to divers is that the Thai islanders are passionate about their ecology and strict about limiting environmental impact caused by diving. You will be expected to comply with their conditions when using their services. There are workshops available, too, where you can help rebuild and protect the coral reefs from further erosion.

Diving is available all year round, though not recommended during monsoon season (November to December) for safety reasons, though some highly qualified divers continue to dive in the safer waters around the gulf.