Mun Islands

Diving Type muck dive, snorkeling

Level All Levels
Depth 2 - 15 meters
Visibility 2 - 15 meters
Current Mild - Moderate
Water Temp 26 - 31 °c
Dive Site Koh Man Nai, Koh Man Klang, Koh Mun Nok, Hin Yuan (Hin Farang), Petra Wreck
Season The best season is during January to April. From November to December it is not too bad, but from May to October is not recommended as the water is quite murky as the rainy season brings a lot of sediment from the river mouth.
Highlight moray eels, pipefish, scorpionfish, butterflyfish, groupers, cuttlefish, giant clams, sea slugs, seahorses, stingrays, octopuses, sea turtles

General Info

It is an archipelago of 3 islands, namely Koh Mun Nai, Koh Mun Klang and Koh Mun Nok, located about 30-45 minutes from the shore.

On Koh Mun Nai, there is a Sea Turtle Conservation Center run by the Department of Marine and Coastal Resources (DMCR). There is no accommodation for tourists. The residents are researchers and DMCR staff. But tourists can purchase a one-day trip to visit the turtle nursery and dive or snorkel around the island.

For Koh Mun Klang and Koh Mun Nok, they are private islands that have only one resort each.

Around this archipelago, there are many healthy and diverse coral reef areas, both natural reefs and artificial reefs, suitable for both scuba and snorkeling, both reef diving and muck diving.

Interesting Marine Life

  • Reef Dive: butterflyfish, groupers, cuttlefish (sometimes you can see them mating), moray eels, pipefish, scorpionfish, giant clams etc.
  • Muck Dive: sea slugs, seahorses, stingrays, octopuses (Often hiding in bivalve shells)

Sea turtles are rarely found, but there has been a record of one hawksbill turtle named 'Kaprao'.


For muck diving, watch out for the flower urchin, poisonous sea stars that are common in the area.

Dive Site (Detail)

Koh Man Nai :
A popular dive site is at the pier where there are many sea slugs hiding, especially on the harbor pillars, looking carefully in hydriod and you may find some tiny nudibranch called Unidentia spp, the species with pink-tip cerata. The rarer species such as Kabeiro rubroreticulata has been spotted on hydroid on the seafloor under the bridge. If you swim out to the coral reef nearby, there are a lot of colorful giant clams in the area.

The western reef of the island further south of the main pier is another interesting spot. It hosts wonderful natural reefs with high diversity of hard corals. It is one of the best sites in the area. There are also artificial reefs in many forms nearby, including concrete blocks that have many coral recruitments. Porcupinefish are often around.

Koh Man Klang : There are coral reefs on the east side of the island.

Koh Mun Nok : There are coral reefs on the west and east sides of the island.

Hin Yuan (Hin Farang): It is a small pile of rocks emerging from the water, located between Koh Mun Klang and Koh Mun Nok. There are hard corals all around the island with full diversity, and it is considered another best spot in this archipelago.

Petra Wreck : Located further south of Koh Mun Nok, this wreck was a royal warship that was decommissioned and sank in 2012 to be an artificial reef. The maximum depth is about 20 meters. One of the common sea slugs here is the famous Doriprismatica atromarginata, which Thai divers often call the Omelet Nudibranch. A whale shark can be seen occasionally.

Go There

These islands are located in Klaeng District, Rayong Province, which can be reached by minibus from Bangkok.

If you want to stay overnight on Koh Mun Klang or Koh Munnok, you can reach the resort directly for transportation. For one-day trips of Koh Mun Nai, there are many tours provided, both snorkeling and scuba diving.

How to Go toRayong


Nearest Recompression Chamber Facility

  • Bangkok Pattaya Hospital: Sukhumvit Road, Pattaya City, Chonburi Province, Tel. 038-259-986, Call Center 1719, Call for an emergency vehicle. Tel. 038-259-911.
  • LifePlus Wellness Clinic, Star IT Center Building, 2nd Floor, Sukhumvit Road, Muang District, Rayong Province, Tel. 065 719 6555