The main dive site at Koh Bon is known by most as Koh Bon Ridge, and it should not to be confused with Koh Bon Pinnacle, which is another dive site just a few hundred metres to the north. These two fantastic dive sites are arguably the very best places in Thailand to see the massive, majestic, but harmless Manta Rays (Manta alfredi) which come here to feed, or be cleaned.
There is no guarantee of seeing Manta Rays at Koh Bon, but they are reported to visit most days late in the diving season, especially in April and May. Normally, this is quite a quiet dive site compared to other diving locations in the area, such as the world-famous Richelieu Rock and the twenty or so dive sites at the Similan Islands.
Koh Bon is located about 22km to the northeast of the Similan Islands' northernmost point. There are no beaches here at Koh Bon, so visits are strictly diving only. Unlike dive sites at The Similan Islands main archipelago, which are made up by granite rocks, Koh Bon is limestone. The dive site is to the southwest corner of the island, which is shaped like a horseshoe. In its cove there is rarely a current, so night dives are possible there. There are two main diving areas at Koh Bon, which are the ridge which slopes off to the west, and the well-known vertical wall. At the ridge, divers can see all kinds of marine life while waiting for Manta Rays, while the wall is claimed to be the most vertical underwater drop off in all of Thailand. It is covered with corals and anemones and goes down to deeper than 40m.
Of course, the main attraction here for divers is seeing Manta Rays, but there are plenty of other wonderful things to see. At the top of the ridge there are scores of coral bommies, which provide a home to thousands of fish and invertebrates. Underneath the ridge there is a sandy bottom where it's common to spot a Leopard Shark (Stegastoma fasciatum) resting. Other common Andaman fish to look out for are species of moray eels (Gymnothorax), Triggerfish (Balistidae), Damselfish (Pomacentridae), Rainbow Runners (Elagatis bipinnulata), Lionfish (Pterois), Batfish (Platax orbicularis), Sweetlips (Plectorhinchus), Banded Sea Kraits/Snakes (Laticauda colubrina) and lots of different invertebrates such as octopuses, cuttlefish, Mantis Shrimps (Stomatopods), crabs, and nudibranchs.
Many divers don't notice the colours of corals and anemones at Koh Bon Ridge. For some reason, the colours aren't as vibrant as those at the Similan Islands, but they are more varied and extremely beautiful. When divers descend the vertical wall that this dive spot is famous for, these colours change and vary.
Each part of the reef is a unique home to different species. Down at the bottom, the light and colour become limited, but this is still a wonderful dive site. However, divers should remember that staying underwater for as long as possible at Koh Bon will increase the chances of seeing something large and interesting. Therefore, avoid going too deep, because this will just shorten the length of the dive. Really, divers need to decide before the dive whether they plan to hang around for Manta Rays, or enjoy a nice and interesting deep dive here at Koh Bon. If it is early in the morning, a deep dive is more practical, and they can possibly even enjoy a second dive on the ridge later in the day to look out into the blue in the hope of these gentle giants passing by.
Diving at Koh Bon is an extremely enjoyable experience and divers nearly always go home with huge smiles and plenty to talk about. How they get there depends on the amount of time they have and their budget. While liveaboard cruises are relaxing and allow for multiple dives and last-minute changes of plan, speedboat day trips get you there and back in a day, leaving time to enjoy other aspects of a holiday in Thailand. We can offer the best-value liveaboards and day trips at unbeatable prices. Just click here to find out more.