Diver's terrifying encounter with monster shark

"And then I would of had a brown mark in my wetsuit", the caption to the video said. Photo / SA Spearfishing / Facebook

A diver has been left counting his blessings after a close but terrifying encounter with a massive shark.

In footage posted to a South African divers Facebook page, an incredibly large shark comes within inches of colliding head-first with the oblivious diver.

The diver can be seen facing the camera, unaware of the shark zeroing in on him.

The shark comes within a whisker of the diver before the diver swiftly ducks his head, avoiding contact with the approaching shark.

The video was posted on Facebook with the caption: "And then I would of had a brown mark in my wetsuit".

Viewers commented on the post, with many saying the diver is lucky to be alive.

"He should buy a lottery ticket, the worst fear of any diver, is that we're not the top of the food chain in the ocean," one person wrote.

Another said the "shark was stalking him. He turned half a second later shark comes in, speeds up, lines up, then something made it reconsider".

"What would you do?? Me being cameraman n seeing that, I'd be running not swimming outta that water", one woman said.

However, some are sceptical the footage is real, with writing "the Great White Photoshop", and another questioning whether the diver was wearing a shark shield.

The video, which was posted on Sunday, has had more than 1 million views and has been shared 21,300 times.