MOMENT OF IMPACT: The 10-metre whale, right, moves its mighty tail near the surfers at Bondi Beach on Sunday.

A former Wellington doctor was hurled into the air and knocked out during a close encounter with a huge whale at Sydney's Bondi Beach.

Bishan Rajapakse, 38, said all he remembered was saying, "Hey, how's it going?" to the whale, which was less then a metre away.

"I remember trying to talk to it . . . before I realised I was off my board and on my front," he said. "Contacting whales is not what it's cracked up to be."

CLOSE ENCOUNTER: Bondi surfer Bishan Rajapaske at St Vincent's Hospital in Sydney

The Sri Lankan-born New Zealander, who has worked at Hutt Hospital and Wellington Hospital, was surfing yesterday morning when his friend signalled him over.

"When I got to him I saw there was this dark, black shadow and it was just massive.

"The whale was moving in like slow motion. It was beautiful and it breached and we could see the barnacles, and it was slowly going up and down and turning and it actually made a noise. It was amazing."

Surrounded by curious surfers, the whale, believed to be a southern right, flicked its massive tail. Witnesses said Dr Rajapakse was flung three metres into the air.

He was knocked unconscious for about 10 seconds, and dragged to shore by fellow surfers.

Witness Lachlan Harris said the whale was "as big as a bus". "It just sent the surfers flying like skittles."

From his hospital bed, Dr Rajapakse said he had no recollection of being thrown off his board. "My mate Chris was there when I came to and was like ‘Bish, you've been hit by a whale'.

"Apparently my face was down in the water and then I was talking to one of the Bondi Rescue dudes. Then I was on the shore and in the ambulance before I knew it."

He had no injuries apart from a slight headache.

Dr Rajapakse joked that the encounter had ruined his plans for the day.

"I was really hoping to have brunch."

Gordian Fulde, director of the emergency department at St Vincent's Hospital, said the incident was a near drowning.

"But he has no broken bones. He will probably go home tomorrow."

Witness Paul Martin, a lifeguard, said the whale "came in 75-100 metres off the rocks" on the southern end of Bondi Beach.

"The whale ran into a group of surfers and decided it was going to play football with one of them."

Bondi lifeguard Anthony Carroll, said the victim was about half a metre from the tail of the whale.

"A local surfer, Tony Spanos, held him up while he was unconscious for 15 seconds face down," Mr Carroll said.

"His board had been smashed in pretty badly. It looked like he was thrown about three metres above the water. The tail of a whale is the strongest muscle on any animal in the world. Some humpback whales get up to 80 tonnes. It's an extreme no-no to go in the vicinity of a whale."

In 2003, Kaikoura man Tom Smith died after he was struck by the tail of a humpback whale that he was trying to free from a craypot line.