A great white shark is thought to have been spotted about 12 miles off the southwestern coast of Bermuda.

A group of friends were fishing at sea mount Challenger Banks last Thursday when they saw a large shark circling their boat. Michiko Campbell, a chef who enjoys fishing as a hobby, told The Royal Gazette: “We were on top of the crown in about 180 feet of water, 12 miles southwest of Bermuda.

“We were chumming for tuna and wahoo and one of the other guys on the boat saw something big below us — we thought it was a whale shark because we’d seen one a few trips before.”

Mr Campbell said the fish was about six feet away: “It came to the top of the water, then circled our boat once, then came around to the back of the boat.

“We have a 29ft boat and judging by the size of the boat the shark looked like it was about 18 to 20 feet long. It was a great white shark, the biggest shark I have ever seen.”

Mr Campbell, whose wife calls him “Cast Away” for his daredevil antics, said his first instinct was to try to catch it.

However, his friends said it would be impossible using fishing equipment on the boat, Live Action. They took a short video, which has circulated on social media.

Choy Aming, of shark research and conservation organisation the Bermuda Shark Project, said: “I’ve looked at the photo a few times and I am 99 per cent sure that it is a great white shark.

“The only other possibility would be an enormous mako, but that is unlikely. Great whites are rare in Bermuda but not unheard of. This is the third sighting I have known about — every sighting has been on a hot, flat calm day in July, funnily enough.

“I would say it was a medium-sized shark, maybe ten feet.”

Mr Aming warned against attempting to catch great white sharks. He said: “First off, they are a protected, endangered species world wide.

“Second, 99 per cent of people are not going to have the gear to handle it. Even if you do get it on the boat you are just going to kill it — nobody is going to eat that meat so it is not a good idea. You would get a trophy shot, that is about it.

“If anybody sees it I would recommend just throwing a few scraps into the water just so you can get it to hang around a bit and get some pictures and have a cool experience.

“There has been a ton of shark activity lately. There seems to be higher than normal shark activity this year, from the reports I am getting. I am starting my trips out this weekend.

“In addition to the usual tiger shark sightings, someone saw a whale shark and there have been lots of dolphin sightings.”