A diver is lucky to be alive after he was pinned to the ocean floor by a Great White Shark off the coast in Perth’s northern suburbs.

Tanveer Dhillon was diving off Ocean Reef on Sunday when a shark began circling him and rammed him into a sandbank.

Mr Dhillon said he wedged himself in a ledge to hide from the shark, which circled him for about 10 minutes as the oxygen in his tank kept depleting.

“I could see the great white grinning straight at me — my heart was in my mouth and now that memory is forever etched in my mind and I still feel the shivers when I see that moment,” he told 7NEWS.

“My first instinct was ‘why is my dive buddy kicking me?’ so I turned around and when I saw that it was not a person, it was a shark, it was sheer panic.”

The 39-year-old said as he hid from the shark he said a prayer that “if I get out of this situation, I’m never going to put myself in this position again because you’re helpless”.

When the shark was finally out of sight, Mr Dhillon raised the alarm with his dive mates — urging them to swim to the safety of their boat.

“His eyes were quite wide and his regulator was out of his mouth so I thought ‘what is going on?’,” his friend Nicholas Black said about the ordeal.

Mr Dhillon now wants to educate other divers on how to stay calm during a crisis.

“If I would have done the knee jerk reaction and gone straight for the surface I feel fairly confident he would have gone for me,” he said.

“This is the shark’s territory and we are just visitors over there and understanding that we have to be mindful of that.”

The frightening ordeal won’t stop the avid diver from doing what he loves but he admitted it would be some time before he got back in the water again.