Daisy Ridley spent months training with Olympian Siobhan-Marie O’Connor for new role

Daisy Ridley spent months training with Olympian Siobhan-Marie O’Connor for her new role as a marathon swimmer.

The 'Star Wars' actress plays plays the lead role in 'Young Woman and the Sea' - a biopic about Gertrude Ederle, an American swimmer who became the first woman to swim across the English channel in 1926, and spent months completing intense training in the Black Sea with British silver medal winner Siobhan.

Director Joachim Ronning told Variety: "I wanted to be on the ocean. I wanted to be in the real elements with Daisy Ridley swimming through the currents and cold water ...

"[Daisy] started training for months and months, open water swimming with Siobhan-Marie O’Connor, the English Olympic medalist swimmer.

"They trained and she learned period swimming - how they swam 100 years ago.

"When she went into the water, she was tough. She never complained and was always going for it, and asking ‘Do you want one more?’ and her lips were turning blue."

Daisy previously revealed the on-camera swimming was pretty tough. She told Deadline at the movie's premiere: "I was really alone in the Black Sea, and I was really trying to keep pace with the camera.

"And then I was trying to keep pace with the boat and the camera boat. I trained for three months and then we were training during filming."

The 'Star Wars' actress added: "And then we did the big swim at the end. So it was nine days in the Black Sea. It was overwhelming. It was cold. Each time, it was scary."