This diver was slapped in the face by a passing whale's fin in this incredible encounter off South Africa's east coast.

Chris Coates was recording as a 13-metre female humpback whale emerged out of the blue with its calf.

The diver is heard screaming with fear as the marine mammal approaches.

Then the whale turns to swim past and flaps a huge fin at Coates, hitting him on the head and arm.

"I could feel its barnacles scraping over my forehead," said Coates. "The slap with the fin was quite hard, but I don't think it was trying to hurt me or it would have been way harder," he added.

Coates said he was pretty surprised when he saw the whale swim so close.

"I must admit I got quite a shock with it swam right up at me. At one stage it was only one foot away, and even though I know that they generally don't hurt people, It's so big and strong it is still scary."

This encounter was captured in September 2013.

While on a free-diving trip up the eastern coastline of South Africa, Chris Coates came way to close to a thirteen-metre humpback whale and nearly paid the price for his risky camerawork.

The massive female whale appeared out of the blue with its calf and swam straight up to Coates. You can hear him screaming with fear and excitement as the animal practically nuzzles the camera. Then whale turns to swim past and flaps a huge fin at Coates, hitting him on the head and arm.

"I could feel its barnacles scraping over my forehead," said Coates. "The slap with the fin was quite hard, but I don't think it was trying to hurt me or it would have been way harder," he added.

Coates said he was pretty surprised when he saw the whale swim so close.

"I must admit I got quite a shock with it swam right up at me. At one stage it was only one foot away, and even though I know that they generally don't hurt people, It's so big and strong it is still scary.