A well-known Australian karate instructor is fighting for his life today after smoking cannabis and then drowning when he went for a swim.

Malcolm Ayles, 58, from Grovedale, Victoria, is said to have smoked the legal drug while sitting with his wife on holiday in Pattaya, Thailand, in the early hours of Monday morning, April 1.

Partner Panadda Ayles, 45, said her husband then jogged along the sand before wading into the chopping sea on the notorious Jomtien Beach - the scene of several accidental drownings in recent years.

However, Malcolm disappeared below the water and shouted for help before heroic local Kittichai Limcharoen, 48, dived into the surf to save the Aussie.

The Martial Arts fanatic, who has featured on the cover of several magazines, received CPR on the beach before being rushed to hospital. He was reportedly in a coma this morning.

Panadda said: 'My husband had smoked two cannabis cigarettes that he bought from a shop near the beach. He told me he was going for a run along the beach.

'I watched him and suddenly he ran into the sea and started drowning before my eyes. I was shocked and shouted for help.

'I still can't believe what happened. My husband is so fit and strong. We didn't have any disagreement. He was very relaxed.'

Kittichai, the man who pulled Malcolm from the water, said he saw the Aussie struggling and heard calls for help.

The Thai local said: 'I saw what was happening and realised that nobody else was there to help the man. I jumped into the water as fast as I could to save him.

'I pulled him back to the sand and then the rescue team arrived shortly after.'

Paramedics said today that Malcolm was taken to hospital and he was still comatose this morning. He is being closely monitored by doctors.

A spokesman for the Sawang Boriboon Dhammasathan rescue volunteer team said: 'This incident was a 'red case'. That means the condition of the patient was the most severe next to fatal. He was unconscious when we took him to the hospital. He was in a coma.'

Malcolm is the CEO and founder of Climate Warrior, the head instructor of Shiryodo Karate, and the owner of Club Administrator Software.