A French tourist drowned while snorkeling off the Similan Islands archipelago in southern Thailand.

Bertrand Georges Victor Lucien Lehoux, 66, was snorkelling near Koh 9 island in Mu Koh Similan National Park when he lost consciousness in the water on January 26.

Rescuers and medics were alerted by the Phang Nga Port Security Control Centre at around 3 pm. They arrived and pulled the tourist back to shore to administer first aid but they found he had no pulse.

The Frenchman was ferried to the Thap Lamu Pier and then rushed to the Khao Lak Medical Centre, where he was pronounced dead.

Officials said he had been riding the 'Wandee' vessel on a snorkelling trip with travel company Sea Star.

Last week, a Chinese man also drowned while swimming off the Similan Islands.

The man, 44, had been swimming near Koh 7 island when locals saw him flailing in the water. He was rescued and rushed to a hospital but was later pronounced dead.