Wildlife photographer Martin Yelland managed to catch the incredible moment on film.
But as the divers snorkelled alongside them, they were horrified to see a hook lodged in the side of the animal’s face.
They believe that the blue shark, which can measure up to 13ft, wound up with the foreign object sticking out of its mouth because of muffed fishing practices.
Martin, a postman from St Erth, told the Sun Online: “Initially, there were two smaller sharks nibbling the bait, but not sticking around for long.
“The only sad thing was she had a hook in the side of her face, due to fishing practices.
“We asked our guide what could be done for the shark, but apparently, even if they could catch the shark, it may cause it even more stress to attempt to remove it, which they might not have been able to do anyway.”
The animals are reported to circle swimmers or divers for 15 minutes or more before going in for a bite – they are “not overly aggressive” but should be approached with caution.
In the UK, the blue shark can generally be found in the warmer waters of the South West though they can turn up elsewhere and have been sighted to the north of the British Isles.
Earlier this year, a shark was seen leaping out of the sea in front of a stunned photographer off the Welsh coast.
The long-tailed thresher shark, which can be up to 25ft long, was snapped making the spectacular leap near Strumble Head, Pembrokeshire.
Snapper Ken Barnett of the Sea Trust was lucky to capture the amazing show.
He said: “Such a great sight to see this thresher shark leave the water at Strumble Head.”
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