You can hear the terror in Eugene van Wyngaardt's voice as the shark first appears and then again when the animal makes very close passes.

The final time the shark comes so close that Mr van Wyngaardt is forced to prod it with his spear gun, both to push himself away from it and to try to deter the monster.

Fortunately, the shark moves away again, giving him time to swim to the boat and frantically clamber aboard. From the boat the shark can be seen continuing to circle menacingly.

"When I saw it swim past, and it turned in such a tight circle so it was right in my face, that's what scared me," Mr van Wyngaardt said.

"I realised the boat was close, and I realised that I could swim at least ten metres fairly safely knowing that it was not going to get me."