Experts say they are taking seriously a reported sighting of a Great White Shark off the Devon coast.
Great White: Nearest confirmed sighting is in the Bay of Biscay
A teenage holidaymaker from Birmingham, who is keen on marine biology, is adamant she saw the creature.
The fearsome predators are most often found in warm temperate seas.
But the National Marine Aquarium in Plymouth says she could be right.
Chaynee Hodgetts, 15, said she spotted the shark through her binoculars off the north Devon coast.
She said: "It was white on its belly and on its back it was grey.
"The fin was black with a ragged back edge.
"It was spitting the fish out after biting them and then going back for them, which is indicative of a Great White."
Great Whites are often mistaken for Porbeagle sharks which are native to UK shores.
Chaynee Hodgetts: Says she spotted a shark through binoculars
But if her information is correct, experts say she did indeed see a Great White.
Rolf Williams of the National Marine Aquarium, said: "Her account is particularly interesting.
"The level of detail she given us helps us to try and pick out whether it was a Porbeagle or that elusive Great White."
The nearest confirmed sighting of a Great White to the South West coast has been 200 miles away in the Bay of Biscay.
A Great White was also reported off the coast near Padstow in Cornwall by a group of experienced fishermen in August 1999.
And there have been a number of other unconfirmed sightings around the South West coast since.
This month two conservationists are scouring the Devon and Cornwall coastline for evidence of Great Whites.
Richard Peirce, 55, from Bude in north Cornwall, has teamed up with South African shark expert Craig Ferreira to explore a 70-mile stretch of the north Cornwall coast in an attempt to locate and tag an animal.