Close encounters with not one but two previously unseen manta rays at Koh Bon in Thailand’s Similan Islands in late March 2022
Manta ray approaching, Koh Bon, Thailand © Chris Mitchell
The island of Koh Bon is Thailand’s main hotspot for seeing manta rays. It’s definitely not a given you’ll see them – I’ve dived here plenty of times when the mantas have not been around – but this is the place where you have the best chance of seeing a manta ray.
There’s a long limestone ridge – like the back of a sleeping Godzilla – that runs from Koh Bon’s shoreline down underwater and out into the depths. There’s a particular spot on the ridge about 26 metres deep where the mantas historically like to visit so most dive groups head for there.
Manta Ray and ramoras, Koh Bon, Thailand © Chris Mitchell
We got super lucky and saw not one but two manta rays, a different one each day on the two days we were there. On both occasions the manta silently glided in from out of the hazy, plankton rich gloom of the water and gracefully cruised past our group of divers, coming within a metre of us and checking us out.
Manta Ray flyover (nickname Jumbo), Koh Bon, Thailand © Chris Mitchell
That moment when a manta decides to approach a group is really special. If you make direct eye contact with a three metre wide manta ray as it passes by you, it’s not something you’re likely to ever forget.
As all the divers in our group did the right thing and stayed still, the manta swept by out into the blue and disappeared from view only to come back and loop around the group a couple more times, clearly still curious about us.
Manta Ray at Koh Bon – nickname Wunderbar © Chris Mitchell
The following morning we went back in the water at Koh Bon at 7 am. After twenty minutes of waiting and scanning the blue, thinking our luck has run out, another manta came to check us out, coming even closer than the one we saw the previous day. This one stayed with us for over half an hour, and was still visible wheeling around the reef as we broke water returning to the surface.
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As our group had taken numerous photos of the mantas, we were able to tell from the markings on the mantas’ underbellies that we had seen two different manta rays over the two days. Each manta has its own specific pattern of markings which act as an unique identifier.
Manta Ray – nickname Jumbo – over the ridge, Koh Bon, Thailand © Chris Mitchell
As there’s some phone signal at Koh Bon, we also sent identification pictures to Manta Trust’s manta ray ID database. The researchers there ran their software to see if the new photos matched the markings of any of the thousands of Thailand manta ray pictures already in there. They didn’t, so that means the two mantas we saw have not been spotted before (or at least photographed and sent to the database). If a previously unseen manta ray is added to the database, whoever sent in the image can give the manta a nickname. So welcome “Jumbo” and “Wunderbar” to Koh Bon – please come back soon!
Koh Tachai fan corals © Chris Mitchell
Our visit to Koh Bon was part of a 4 day liveaboard trip on MV Smiling Seahorse at the end of March 2022 where we also visited Koh Tachai, Richelieu Rock and the Surin Islands.
After a murky start in the Surin islands we got some fantastic conditions on subsequent days at Tachai and Richelieu. Richelieu in particular was dizzying with the amount of fish gathered together, a huge school of jacks circling just off the rock the highlight. It felt like anything might show up at both Tachai and Richelieu, the water full of life and action.
School of Jacks with James, Richelieu Rock, Thailand © Chris Mitchell
Big thanks to James for being a great dive guide and patient model. And thanks to Franck and the team on Smiling Seahorse for another great trip. Franck got some fantastic photos of the second manta ray at Koh Bon which you can see in his own trip report.
Update: another epic manta ray encounter at Koh Bon in February 2025
Richelieu Rock soft corals suffused with glassfish © Chris Mitchell
Similan Dive Sites
Richelieu Rock
Thailand’s best dive site, bar none. A stunning array of soft corals and spectacular stampeding marine life. Read More
Koh Bon
Thailand’s manta ray hotspot, with plenty of other things to see if the mantas don’t show up. Read More
Koh Tachai
Koh Tachai is one of the Similan Islands’ best dive sites but also one of the most volatile. Massive fans, huge schools of fish, maybe manta rays – it’s all to play for. Read More
Boulder City
A dramatic deep water Similan dive site, Boulder City needs the right conditions to explore as it’s exposed to wind and wave from all sides. Read More
Shark’s Fin Reef
A dramatic block of rock rising out of the sand, Shark’s Fin Reef is one of the Similan Islands’ most exciting sites. Read More
Hideaway Bay
Two Similan Islands dive sites in one location, Hideaway Bay and Tuna Wreck can be experienced in a single dive. Read More
North Point
North Point is another of the Similans’ signature big boulder sites, with huge great rocks rising out of the white sand. Read More
Koh Bon Pinnacle
Koh Bon Pinnacle is a deep dive site that feels utterly remote – and where anything could show up out of the blue. Read More
West Of Eden
A big boulder site with spectacular outsize fan corals, beautiful soft corals and the promise of full fish activity, West Of Eden is an archetypal Similan Islands dive site. Read More
Ao Suthep, Surin Islands
Ao Suthep is beautiful hard coral garden in the Surin Islands, often visited by Similan island diving liveaboards and accessible by snorkellers visiting the Surin Islands too. Read More
Three Trees
Three Trees, named after the three trees directly above the dive site on Similan Island 9, is a big wide white sand channel with some awesome corals and fish encounters. Read More
Christmas Point
One of the signature Similan Islands big boulder dive sites, Christmas Point’s huge rocks have been shaped by the tides over hundreds of years. Read More
