Snorkeling & Driving  :  The best diving season is between October/November and April. The best sites are on the west and southern tip of the island, between Koh Chang (Ko Chang) and Koh Kood (Ko Kut). There you can see soft corals, anemones, myriad reef fish, and sometimes eel. Hin Luk Bat and Hin Lap both have coral seamounts. Further south, white-tip reef sharks can be found near Hin Phrai Nam.

In addition, there are two wreck dive sites. The Koh Chang (Ko Chang) Wreck is a Thai warship sunk by the French navy in 1941. The wreck is only 15 metres deep in the Salakphet Bay on the southern tip of the island. The other wreck is the Pak One Wreck which sank after hitting a coral reef in August 1996 on its way to Vietnam. It resurfaced almost 8 years later. The 900-ton sunken tanker posed a danger to ships on international waters. The Royal Thai Navy drained off its 600 tonnes of liquefied petroleum gas and resank it between Koh Chang and Koh Samet. It now lies horizontally in 35-metre-deep waters.

There are a few diving centres on Koh Chang (Ko Chang) such as the Ploy Scuba Diving in Bang Bao. They provide free transfer to and from the resort. Language barrier is no problem to the centre since they provide instructions in different languages. Following the standards of the sister centre in Koh Samet, this is the premier diving operator in Eastern Thailand.

Viewing Fireflies  : During the cooler months on Koh Chang (Ko Chang), you can rent a boat to slowly cruise along the waters at night to see fireflies in the mangroves. Thousands of fireflies send out mating signals as they settle into the mangrove forest, lighting up the whole tree with their simultaneous flashing in the dark. It's like rows of Christmas trees. Hotels like the Koh Chang Grand Orchid Resort & Spa and the Aana Resort & Spa provide information on where to go to spot the fireflies and boat service.