Julia Roberts has done it with orangutans. Goldie Hawn did it with Asian elephants. And Bob Hoskins did it with tigers. Now EastEnders actress Tamsin Outhwaite, more used to mixing with the wild life in Albert Square, is going swimming with dolphins.

She's following a long line of celebrities who've abandoned the luxury of trailers and air-conditioned studios for unpredictable, and sometimes inhospitable, foreign locations.

Outhwaite - who's announced that she's quitting as EastEnders' Mel next year - swims, works and communicates with dolphins and learns how they are helping children with special needs.

The programme, Tamsin Outhwaite Goes Wild With Dolphins, comes not long after Silent Witness actress Amanda Burton starred in Born To Be Wild, in which she became part of a team rescuing orphaned black bear cubs in the mountains of Idaho. Afterwards, she and her husband, photographer Sven Arnstein, returned to check on the bears' progress, fitting in visits between her BBC filming commitments.

The attraction of such programmes for a celebrity is not just a free foreign trip, but the chance to do something they wouldn't be able to do as an ordinary member of the public. It's a bonus of being famous, just like getting the best table in a restaurant because of your name.

For the broadcaster, the presence of a famous face ensures good ratings for a subject that might otherwise be passed over as just another wildlife or nature programme. Just as David Attenborough is as much of a draw as the documentaries he narrates, or Rolf Harris is one of the reasons people watch Animal Hospital.

Gary Broadhurst, director of the Outhwaite documentary, feels it's vital not to cast a celebrity just for the sake of it. Outhwaite's name came up when his team were discussing whom they could get to front the dolphins programme.

"She was really interested and, because she was doing very well at EastEnders and was the face of the BBC at the time, we thought it was a good pairing," he explains. "The way BBC1 in particular is heading, a lot of the programmes are celebrity driven, whereas BBC2 is much more experts and specialists. I wouldn't have been interested unless someone was going to give 120 per cent - which Tamsin did.

"The other reason for doing an animal documentary with a big name is intrigue value. People want to see the other side of that person. She's not Mel from EastEnders, she's herself. It's quite revealing."

The pairing was a good one as Outhwaite's had a long ambition to swim with dolphins. "If I was asked to name my favourite animals, dolphins would win, hands down," she says. "I don't know why, but I've always been fascinated by them. From an early age, I knew I wanted to act, but second on my list of ambitions was to come face-to-face with a dolphin."

Casting someone famous brings its own problems, mainly fitting filming into their busy schedules. Tamsin and the dolphins was made over 18 months, with the actress having to take two breaks from Albert Square to film in Florida and the Bahamas. "There's a huge amount of planning involved, especially with foreign shoots and wanting to work with the research team. There were only certain times of the year they take their boats out," says Broadhurst.

Happily, Outhwaite slotted into the project immediately. "She was slightly apprehensive because she'd never done any documentary film-making before," he says. "So we spent a lot of time explaining how everything worked. We put her in a situation and let her get on with it. It was not scripted. The thing that came really naturally to her was turning to the camera and saying what she was thinking at the time."

There was no guarantee that she'd get to swim with dolphins. At one point, bad weather and sharks threatened to keep the dolphins away, although it worked out in the end. Broadhurst recalls that when Hollywood funny man Robin Williams was making a dolphins documentary a few years ago, he and the film-makers spent a week at sea and didn't see any dolphins. They had to return later.

Celebrities don't seem to mind roughing it on the animal trail. Julia Roberts earns 20 million dollars a movie, but was paid considerably less when she travelled to the Indonesian island of Borneo to see orangutans.

Holly Hunter, an Oscar-winner for The Piano, travelled thousands of miles by plane, train, Land Rover and foot in search of cheetahs in Namibia.

Another Academy Award winner, Richard Dreyfuss, spent three weeks in the Galapagos Islands, where he came nose-to-nose with a marine iguana, sat next to a pair of dancing albatross, and sneaked up on a pair of amorous tortoises.

Goldie Hawn got to bathe Asian elephants in India, and learnt how to ride them. Anthony Hopkins was able to act on his endless fascination for lions by seeing the king of the beasts in East Africa. An Officer And A Gentleman star Debra Winger took her son Noah in search of a wild panda, on a journey that took them by boat, train and rickshaw from Shanghai to the remote Quinling mountains in China.

For some, what seemed like a holiday with a bit of filming thrown in, turns into a life-changing experience. Bob Hoskins said, after seeing tigers in Indonesia and the foothills of Nepal: "It was magic. It was like fire on four legs, and it pulled at things in me that went back further than being born".

* Tamsin Outhwaite Goes Wild With Dolphins is on BBC 1 on Thursday at 9pm.

Published: Saturday, December 1, 2001