Manta Ray

Manta rays are among the most charismatic animals in the ocean. With wingspans reaching 5–7 metres in the case of the oceanic species, and a grace of movement that makes them seem to fly rather than swim, a manta encounter is one of diving’s definitive experiences.

In Thailand

Thailand hosts both the Oceanic Manta Ray (Mobula birostris) and the smaller Reef Manta Ray (Mobula alfredi). Both species are regularly encountered, with Hin Daeng and Hin Muang near Koh Lanta being the undisputed premier sites. Koh Bon in the northern Similan group is excellent from January to April.

Feeding Behaviour

Mantas feed by filtering plankton through their gills as they swim. The “cephalic fins” — horn-like appendages on either side of their head — funnel water into the mouth. At Hin Daeng during peak season, it’s common to see multiple mantas performing “barrel rolls” — spiralling upward through plankton-rich water, looping back, and spiralling again in a continuous feeding circuit. This behaviour, observed from below with the rays silhouetted against blue water, is among the most beautiful sights in all of diving.

When and Where

• Hin Daeng/Hin Muang: January–April, reliable aggregations
• Koh Bon: December–April, oceanic mantas
• Richelieu Rock: February–May, occasional
• Similan Islands: December–April, cleaning stations

Conservation

Both manta species are listed as Vulnerable on the IUCN Red List. Numbers have declined due to targeted fishing and bycatch. Never touch mantas, always maintain respectful distance, and avoid surrounding or cutting off a feeding or cleaning ray.