Marine researchers are predicting that sightings of one of Britain's oldest species will increase because the sea around the UK is getting warmer.
Researchers have been using satellite tags to monitor the turtles
Leatherback turtles, which have been around for over 65m years, are most often spotted in August and September.
A research team at Swansea University has been using satellite tags to track their movement and behaviour.
Data suggests they are driven by water temperature and the numbers travelling further north have already increased.
Appearances by leatherbacks in UK waters are seasonal and it was thought they were linked to either the availability of food such as plankton or the temperature of the sea.
Swansea University professor Graeme Hays has led international efforts to save the turtle from extinction.
He said plankton surveys showed that it could be found in abundance in the spring, summer and autumn which contrasted with the sightings of leatherbacks which were mainly in late summer.
The turtles can grow up to 2m
Due to their size, adults have few natural predators
The species is endangered as they are accidentally trapped in tuna and swordfish nets
He said tracking data confirmed the leatherbacks headed south once the water started to cool.
He said over the last two decades the North Atlantic waters had warmed with more temperate water being found further north each year.
Based on this oceanographic data he said it was likely turtles were travelling up to around 330 kilometres further north each year than they were 20 years ago.
"Twenty or thirty years ago there would just be a handful who would come up this far," he said.
"Now the ones we are seeing are no longer stragglers but are routinely coming up to forage.
"As areas warm, so species have been found to expand their range while others contract.
"Assuming the temperature of the seas around the UK continue to rise, we can expect to see even more of these amazing creatures in the years to come."