This is the incredible moment whales were seen catching fish in their mouths off the coast of Thailand.

Drone footage shows one the large cetaceans stretching its mouth open to gulp down dozens of fish off Samut Songkhram province on August 10. It then sank back into the sea to rejoin another whale swimming nearby.

The behaviour, called trap-feeding, involves whales lurking just under the surface of the water with their mouths open to lure schools of unsuspecting fish.

Parinya Phadungthin, who operates whale-watching tours in Samut Songkhram, said: 'It's better to use drones while whale watching because you get a clearer perspective of just how large the whales are.

'I could feel my hands shaking from excitement because of how thrilling it is to watch these spectacular creatures in the water.'