Dressed in only a slip and baring all of her thin frame for the cameras, the actress chose to take on her own underwater stunts for the film Atonement.
Looking angelic as a mermaid and showing off her tiny frame, Keira Knightley took to the water easily as she films this scene dressed only in a silp and surrounded by lilies
In cold temperatures Keira braved the water for the scene in which she jumps into a pond in order to fetch a vase dropped by her love interest, played by James McAvoy.
Dressed in nothing more than thin satin underwear, Keira's character, the ice queen Cecilia, manages to retrieve the urn.
A quick gasp of air from a scuba tank and Keira is ready to act again as she is surrounded by a better kitted-out crew on Atonement
Then, wrapped up in a little more clothing - Keira films a different scene wearing a tight blue dress.
In this second scene, the actress had a huge acting challenge to play Cecilia as the London Underground station of Balham is flooded.
Floating down through the water, Keira Knightley proves she will push herself for the part in this underwater stunt
The Atonement actress proved her versatility with this underwater stunt - no flippers, snorkel or diver's tank for Keira
The station is bombed, and while Keira is not hurt by the blast, she is caught up in the ensuing flood. The scene is one of the last filmed for Atonement, released during summer in Britain and now playing in the US.
Since filming Atonement, Keira has gone on to resume her usual garb of period costume as she plays 18th century English socialite Georgiana Spencer.
