Koh Racha Yai offers a diverse underwater environment featuring a combination of natural reefs, wrecks, and artificial reef structures. Located in the Andaman Sea, this site is accessible only by boat and is suited for intermediate divers. Depths range from 3 to 30 metres with an average of 15 metres. Divers should be prepared for moderate currents that can shift in direction and strength. Visibility fluctuates between 5 and 25 metres, while water temperatures remain warm, typically between 28 and 30 degrees Celsius. Due to active boat traffic, divers must deploy a marker buoy before ascending. Always maintain buoyancy to avoid contact with sharp coral and rocky structures.

Ao Sane beach on Koh Racha Yai offers an accessible shore dive suitable for beginners. The reef topography sits at depths between 6 and 14 metres, with an average depth of 12 metres. Divers typically experience mild currents and visibility ranging from 5 to 10 metres. The site is well-equipped with parking, toilets, showers, and a rinse station, alongside a local dive shop providing air fills and guided tours. Night diving is permitted here, offering a different perspective of the reef environment. Species recorded around this area include various moray eels, wrasses, butterflyfish, and lionfish. Be aware of sharp coral when entering and exiting the water.

Yanui beach on Koh Racha Yai offers a shallow reef environment suitable for beginners and open water training. The site features a hard coral reef set against a sandy bottom, providing clear topography for navigation practice. Divers and snorkellers can expect depths ranging from 8 to 14 metres, with an average depth of 10 metres. Entry is made directly from the shore. Conditions are generally mild, though visitors should be aware of potential surf, strong currents, and the presence of sea urchins and sharp coral. Typical dives last around 45 minutes, and the site is accessible for night diving.

Nui Beach on Koh Racha Yai offers a reef environment suitable for beginners, with depths ranging from 5 to 18 metres and an average of 10 metres. Access is via the shore, and the site features a beach club with toilets, showers, and a cafe. Divers and snorkellers should be aware of potential hazards including surf, jellyfish, sea urchins, sharks, and variable visibility between 5 and 15 metres. Currents are generally mild. Species recorded around this area include the black-orange dragonet, laced moray, titan triggerfish, checkerboard wrasse, white-eyed moray, powder-blue surgeonfish, brown butterflyfish, striped surgeonfish, white-spotted puffer, scorpionfish, bluespine unicornfish, blue-spotted urchin, snake eel, and dotted anemone crab.

South Point at Koh Racha Yai offers reef diving for intermediate divers, with depths ranging from 8 to 25 metres. The site is accessed by boat and features moderate currents that can strengthen quickly, requiring good buoyancy control. Divers can explore the reef structure, which provides shelter from water movement. Marine life recorded at this site includes the laced moray, wrasses, vagabond butterflyfish, porcupinefish, crabs, azure sea stars, sergeants, rabbitfish, and various snails. Visibility typically spans 15 to 30 metres. Due to the current patterns, booking a guided tour is recommended to ensure safe entry and drift planning.

WaterPro is a reef site located 1000 metres offshore at Koh Racha Yai, Thailand. The site features a depth profile ranging from 5 to 30 metres, with an average depth of 15 metres. Divers access the reef via boat, which is required due to the distance from shore. Conditions include moderate currents and visibility typically between 20 and 40 metres. Water temperatures remain consistent between 28 and 30 degrees Celsius. Due to the presence of surge, sharp coral, and potential for unpredictable currents, this site is suited for intermediate divers with strong buoyancy control. Surface boat traffic requires caution during entry and exit.

Barracuda Rock is a submerged pinnacle located off Koh Racha Yai, Thailand. This advanced drift dive ranges from 5 to 30 metres in depth, with an average of 15 metres. The site features a structure covered in hard and soft corals and sea fans. Due to the location, strong currents are common and can accelerate quickly around the pinnacle. Visibility is variable, ranging from 5 to 25 metres. Divers must use boat access to reach this site. Night diving is permitted. Given the potential for strong currents, low visibility, and sharp coral, this site is suited for experienced divers who can manage their position and maintain group contact.

Sea Bees at Koh Racha Yai offers a diverse underwater landscape featuring a combination of reef, wall, pinnacle, and cave formations. Accessible only by boat, the site is suitable for beginners, with depths ranging from 10 to 30 metres and an average depth of 20 metres. Visibility typically spans 15 to 30 metres, and currents are generally mild. Water temperatures remain between 28 and 30 degrees Celsius, though cold water intrusions of 25 degrees Celsius can occur in February and March. Night diving is available, and divers should be mindful of boat traffic, sharp coral, sea urchins, and stonefish while maintaining proximity to their guide.