An American tourist was left in a coma after being caught in rough waves on a Thai beach.

Robert Martin, 77, waded into the choppy sea before being struck by a large swell at Jomtien Beach in 'Sin City' Pattaya on Saturday, June 21.

The pensioner, who had recently been treated for muscle weakness, screamed for help as he was knocked off balance and dragged out to sea.

He sank as frantic tourists and lifeguards dived into the algae-infested brown-green water to save him. They managed to rescue him after several minutes, but he was unconscious with a very faint pulse.

Lifeguard Thongchai Thiangcharoen said: ‘Today, the waves and wind were quite strong. Tourists saw the American man going to swim in the water when he was struck by waves and fell over.

‘Nearby tourists helped search for him before pulling him up to shore and calling lifeguards for assistance.'

Dramatic footage shows paramedics pumping the American's chest as they carried out CPR. They also used a defibrillator to shock him before rushing him to the Pattaya City Hospital, where he remains in critical condition.

Brain damage occurs within four minutes of the brain lacking enough oxygen.

Drownings are a recurring safety concern in Thailand, especially in tourist hotspots like Phuket, Pattaya, and Krabi. The deaths are often attributed to strong rip currents, lack of swimming skills, and disregard for warning signages.

The waters are most dangerous during the country's rainy monsoon season, when red flags are placed in beaches to warn of dangerous sea conditions.

Thailand and neighbouring countries in Southeast Asia are in their annual monsoon rainy season which sees soaring temperatures followed by powerful rain storms in the afternoon leading to widespread flash floods.