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.
Recommended Similan Liveaboards October 2025 to May 2026
Blue Dolphin Liveaboard
A mid-range liveaboard with 7 cabins for 16 people. Check availability and pricing
The Phinisi Liveaboard
A Similan mid-range liveaboard with 7 cabins for 18 people.Check availability and pricing
Smiling Seahorse Liveaboard
A mid-range liveaboard with 8 cabins for 16 people. Check availability and pricing
The Junk Liveaboard
A mid-range liveaboard with 6 cabins for 18 people. Check availability and pricing
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
