"I mean the final fight is just all rain, so I’m not quite as keen on that as I am on just being underwater. You stay warm, it’s like 80 degrees in the water and it’s great - swim down, hold your breath, swim back up again.

"But this whole being wet for like five weeks - which is what we’ve been - is quite challenging."

Keira’s ’ugly lips’ - May 15 2007
Keira Knightley has revealed magazines have refused to use her as a cover girl because she had "ugly lips".

The Pirates Of The Caribbean star, who is back on the big screen in the final instalment later this month, said she had been "hurt" by the comments.

"I’ve been told by magazines that they didn’t want to run my picture on the cover because I have ugly lips. Even though I don’t want to care, it does hurt when people talk about you in a bad way," she told the Daily Mirror.

The 22-year-old - who’s repeatedly made a string of sexiest women lists - has spoken out about the pressures to look perfect in Hollywood, as well as hitting out at accusations that her slender figure is the result of an eating disorder.

"It’s sick the kind of pressure put on young women in the entertainment industry," she said.

Keira won’t be showbiz mum? - May 14 2007
Keira Knightley has revealed she hopes to have children one day - but has hinted that she won’t start a family while she’s a star.

The Pirates Of The Caribbean actress - who is romancing actor Rupert Friend - recently hinted that she may quit acting.

And it seems she might put off having kids until then.

"I couldn’t have them in the situation I’m in now but it’s definitely something I see for myself if I do do something else," she says.

Keira recently revealed she wants a "life" instead of stardom.

The 22-year-old told Elle magazine the pressures of fame have become too much.

"The celebrity thing is completely crazy. I think I just have to move away or give it up altogether," she said.

The star added that she reached her decision after a trekking holiday in the Himalayas.

"I spent 10 days in a place where no-one knew me or cared what films I’d been in," she said. "I got to have some total peace and balance and see myself as a tiny insignificant speck - something I really needed."

Keira is stripping off - May 13 2007
Actress Keira Knightley says she is stripping off on screen so often that film fans will soon be pleading with her to keep her clothes on.

"I have certain tools. One of them is my body," she told Total Film magazine.

The 22-year-old is currently shooting The Best Time Of Our Lives with Sienna Miller, about two women who enjoy a relationship with Welsh poet Dylan Thomas.

And she is soon to appear in Silk, an adaptation of the erotic novel by Alessandro Baricco set during the 19th century. "There are plenty of sex scenes in the book, so the adaptation is true to its source," Knightley said of her role in the film.

"I think soon, people are going to insist I keep my clothes on.

"I wouldn’t do anything I didn’t feel completely comfortable with. I suppose I’m very European in my attitude to my body. I’m an actress. I have certain tools. One of them is my body. I don’t mind stripping off occasionally."

Knightley will next be seen opposite Orlando Bloom and Johnny Depp in the third Pirates of the Caribbean film, which opens later this month.