The great thing about Koh Chang is that diving is excellent all year round. As it enjoys a warm tropical climate, the air and ocean is temperate no matter the season, with very little fluctuation throughout the seasons. The three main seasons are the dry, cool season, which is from November to February, the hot season from March to the end of May, and the rainy season, which normally starts around the end of May and continues until the end of October. 

For diving in any of the islands around Koh Chang, the best time is often said to be during the dry, cool season, which normally runs between November and April. In this season, water temperatures linger around a very comfortable 28°C-30°C (82°F-86°F), while air temperatures are about 27°C-30°C (80°F-86°F). This time is also the high tourist season, and the weather is mostly sunny with clear skies, with the odd thunderstorm here and there. The visibility is at its best, which is why many divers choose to dive during this time. 

Diving is still great during the rainy season from May to the end of October, and the ocean is very warm. The only change observed is, of course, more rain, but also lesser visibility, though not dramatically. The seas can be a bit choppier in the rainy season, meaning some dive sites can be difficult to reach, but there are calm periods too. Plus, the ocean critters remain unchanged all year round, so you’re sure to experience fantastic dives no matter when you choose to do so.

The diving in Koh Chang is mostly what you can expect from any tropical paradise - beautiful reefs teeming with a myriad of colorful fish and sea critters. The reef diving is excellent, and suitable for both beginners and advanced divers. 

Wreck diving is also popular, with lots of shipwrecks to be explored that have all been taken over by nature. What’s more, Koh Chang has Thailand’s largest wreck, The 100 meter-long HTMS Chang, which was sunk by the Thai Navy in 2012 in order for it to serve as an artificial reef.  At around 30 meters the vessel touches the ocean bottom, while the captain’s cabin and mast are only at around 12 meters, making it accessible to both experienced and novice divers.

Koh Chang houses a whole boatload of diverse marine species, from tiny macro critters, all the way up to the big stuff, such as barracuda and sharks. Divers can encounter tons of exotic fish like anemonefish, batfish, boxfish, grouper, parrotfish, schools of snapper, harlequin sweetlips, angelfish, and so much more. Titan triggerfish are quite common too, as are moray eels, octopus, blue-spotted stingrays, lionfish and scorpionfish. Macro lovers can gaze at nudibranchs, Christmas tree worms and more. Bigger boys, like great barracuda, can be seen, as well as a few species of shark, like bull sharks, leopard and reef sharks. Friendly sea turtles, including green and hawksbill, appear frequently, and if you’re lucky, you may even spot a whale shark passing by. 

If you choose Koh Chang as your next dive destination, you’re bound to have memorable dives in beautiful tropical waters. There are plenty of dive sites to choose from, suitable for dives if all skill levels and experience.

It’s hard to say which are the best spots to dive, because there are so many that are all unique. But no matter where you dive, you’re in for a treat. To list but a few of the favourite sites in the area, we’ll start with one of the most famous - The HTMS Chang. As mentioned, it’s the largest shipwreck in Thailand, and hosts a plethora of marine species, including colorful reef fish, grouper, squid, octopus and barracuda. In the high season, whalesharks often come to the wreck, so if you’re lucky you might be graced by the presence of this spotted gentle giant. Thanks to the popularity of the HTMS Chang, another vessel was sunk to act as an artificial reef. Wreck of the T11, formerly known as the USS PGM-71, is a 30 meter-long tug boat that sits at around 16 meters. As it’s shallower than its much larger sister, this vessel is perfect for beginners to experience their first wreck dive.

Hin Luk Bat, a large ocean pinnacle, is a beautiful site situated around 30 minutes boat southwest of Bangbao. It plunges down to more than 20 meters, and is home to large schools of fish and a wealth of pretty reef fish. 

A little further south of Hin Luk Bat is Hin Rap, which is similarly a pinnacle that hosts lots of staghorn coral and a diverse number of reef fish. It’s a shallower dive st only around 16 meters, meaning it’s great for those with less experience. 

One of the deepest sites around Koh Chang is Hin Kaduang, which is a site featuring two rocky pinnacles that drop down to around 30 meters. Divers can enjoy tons of rich tropical marine life here, in addition to encountering turtles and reef sharks. 

Koh Rang is also an unmissable area, where there are small islands and rock pinnacles dotted around its entirety. Perfect for divers and snorkelers alike, the diving here is relatively shallow, with most dives ranging between 10-15 meters. Koh Thian, just off the north east coast of Koh Rang, boasts exhilarating scenery and an abundance of life, which is why it’s a very popular spot. 

Koh Yak is another great site, and is mostly only around 10 meters deep, so divers can enjoy long, relaxing shallow dives and marvel at the abundance of coral, pretty reef fish, anemones and many more curious sea critters. 

Koh Kra, located off the north coast of Koh Rang has sloping reefs that are home to a variety of coral and vibrant reef fish. Perfect for beginners, the reef is very shallow and a ton of life thrives. Akin to diving in a colorful aquarium, this spot is recommended for underwater photographers thanks to natural sunlight being able to illuminate the shallow coral. 

Finally there’s Koh Wai, another site that promises exceptional diving in the area. It is known to be one of the best places around Koh Chang to spot reef sharks. Divers can also see plenty of colorful coral and pretty reef fish. Leopard sharks can also be seen here, so keep an eye out.