Shark breaking into diver's cage is the stuff of nightmares

This video is probably every person's worst nightmare: a great white shark breaching the side of a diver's cage while he was still inside.

Terrifying as it seems, though, it is a rare and complex event, as explained by the father of Californian boys Gabe and Garrett, who posted the video on their YouTube feed.

"What might appear to be an aggressive great white shark trying to attack the cage, this is not the case," he explained.

"These awesome sharks are biting at large chunks of tuna tied to a rope. When a great white shark lunges and bites something, it is temporarily blinded."

Filmed during a diving trip to Guadalupe island, Mexico, the footage shows the shark thrashing around and breaking the metal of the cage while chasing the tuna bait.

Swiftly, the boat crew lifts the top of the cage and the blood-covered shark is able to wriggle on its side and get out into the open water.

A single diver was inside the cage, but luckily he managed to end up outside the bottom of the cage. Being a very experienced dive instructor, he remained calm and waited until the shark thrashed out. He was met by applause as he climbed out completely uninjured.

We have no further news on the shark, although it appeared to be injured as it tried to get out of the cage.