This is the heroic moment the navy rescued six fishermen whose boat sank at sea in southern Thailand.

The fishing crew had sailed out to deploy fish traps in Krabi province on January 13 when their boat, the Praew Ploy, started slowly filling with water. The fishermen inspected the vessel and, finding that it had an unrepairable water leak, started calling for help.

Mu Ko Lanta National Park staff spotted the boat after hearing the men's cries near Ko Ha island. A patrol boat was then sent to bring them to safety.

Footage shows the six crew members climbing onto the rescue boat just minutes before the Praew Ploy was submerged in the water.

The fishermen have been taken to the national park and are now safe, but officials were unable to retrieve their boat because it reportedly sank too quickly.

The Mu Ko Lanta National Park head said: 'A patrol boat near Ko Ha was sent to rescue the fishermen as their boat was sinking. Praew Ploy sank so fast that we couldn’t salvage it.'