According to Tom Doyle, a marine biologist from University College Cork who is monitoring the turtle: "We have a new location. For the last three or four days we've got stuff every day. She hasn't gone in a beeline for Ireland as we had hoped. She might be going to Iceland.

She could turn northeast or south. Nobody knows."

The turtle's website (www. turtle. ie) will be updated with this new information this weekend. Most information about the movements of giant leatherbacks in the north Atlantic is new. It is known that they come to feed on shoals of jellyfish, and that they return to the beach in the Caribbean, where they were hatched, to lay their own eggs. They mate once every two or three years, and it seems that this turtle may have decided to give it a skip this year.

When the 65-stone female was brought ashore by Dingle fisherman Padraig Frank O'Sullivan last August, she was the first leatherback to be electronically tagged in European waters. Sightings of turtles . . . about 10 a year . . .are not uncommon off Ireland and Wales. Tom Doyle says Cape Clear is the best place.

But back in August he was about to abandon the EU Interreg Irish Sea Turtle Project when this particular turtle was found, tangled in a rope running between one of Padraig Frank O'Sullivan's lobster pots and its float. Tom Doyle and his colleague from the University of Swansea, Jon Houghton, were in Wales.

"We'd given up, " remembers Tom Doyle. "The tags had been sitting on a shelf in my house for two years."

The satellite tracking devices are not allowed on commercial aircraft without special permission, so Tom Doyle and Jon Houghton got the ferry from Swansea to Rosslare and drove as fast as they could to Dingle. Tom had been working with the salmon fishermen of the area.

The turtle had been brought into Cuas harbour, near Ballydavid in the Kerry Gaeltacht, which is also known as Brandon Creek.

According to local people it was from Cuas harbour that St Brendan left on his journey to America in the sixth century. It was also from this harbour that Tim Severin left to sail the Atlantic in a repetition of the St Brendan voyage, more than a decade ago.

The children at the local school have called the turtle Cuas.

During her captivity of less than 24 hours the turtle did not seem too stressed. "She's a reptile, " says Tom Doyle.

"Although they are definitely aware of you they respond by trying to escape, or by resting."

The next morning she was released from her temporary home in an open-air seawater tank at the Dingle Oceanworld Aquarium. Tom Doyle was not emotional: "I was just: 'let's get the tag on her and get her back to sea'."

Thus began a heroic journey of more than 5,000 miles, as the turtle swam to the coast of west Africa. And thus began worrying times for the people monitoring her. "If the tag misfires the problems usually come in the first five or six hours, " says Tom Doyle.

But the real nail-biting took place months later, when there was no signal from the turtle's tag for six or seven weeks. "The fellas in Swansea are very experienced with tagging and they were saying 'This could be it', " says Tom Doyle. "Tags are susceptible to bio-fouling when small animals grow on them, like on the bottom of a boat."

What saved the whole project was the back-up mechanism, which can predict when the turtle is coming to the surface by looking at her pattern of dives. "We have the guys at SMRU (Sea Mammal Research Unit) in St Andrew's in Scotland to thank for that. When we got a signal from her again after two and a half months we were over the moon."

But it was getting the tag on her in the first place that was the winner. Of the seven species of sea turtle, the leatherback is the most mysterious. They cannot even be accurately aged, as the other types can. They roam over a huge area, foraging in the north Atlantic, whereas other turtles migrate between fixed points.

Tom Doyle is funded by UCC, National Parks and Wildlife and the Marine Institute. For him the mystery of leatherbacks has never faded. "I grew up in Arklow and it's great to be studying this huge marine animal that I never knew existed."

In 1992 he qualified as an electrician with the ESB. "But there was always a niggle at the back of my mind that I'd like to do this. My dad was very into wildlife, we watched all the wildlife programmes together." At 22 he studied at Galway-Mayo Institute of Technology and then zoology at UCG.

"A lot of my best mates are still electricians, " he says. "If I was an electrician I'd have five houses or something by now. For sure, it's less money and it's a struggle. But I do it for the pure joy of it."

He is now completing his PhD on leatherbacks and their food, jellyfish. He began to get urgent emails from people wondering what had happened to the turtle.

The greatest threat to leatherbacks are the long, hooked lines used in tuna fishing. It is predicted that the turtle will be extinct in the Pacific in the near future.