Keira Knightley has had some incredible roles over the years, from a fun teen comedy, Bend it Like Beckham, to Pride & Prejudice, to Atonement, to The Imitation Game. But for many fans, she’ll always be Elizabeth Swann, the fearless, sharp-witted heroine from the Pirates of the Caribbean movies.

And while she made swashbuckling and sword-fighting look easy, it turns out filming wasn’t always smooth sailing for the actress—especially when it came to stunts.

In a behind-the-scenes clip recently shared by the Instagram account Cineatomy, Knightley revealed that she initially thought the movies based on theme park attractions would be a breezy job.

But she quickly realized the action-packed role had other plans for her. She recalled:

One particularly nerve-wracking moment came when she had to perform a high dive off a ship’s plank. She admitted that standing on the plank for two whole days had her completely petrified.

When director Gore Verbinski told her she didn’t have to go through with the stunt, she wasn’t about to back down. She continued:

Talk about dedication! And while she may have been terrified, she was all smiles once she hit the water. She recounted:

It’s safe to say Knightley’s Pirates of the Caribbean experience was far more in line with the best action movies than she anticipated. From epic sword fights to daring escapes, Elizabeth Swann held her own alongside Jack Sparrow and Will Turner, proving to be one of the franchise’s best characters.

Though she bowed out of the series after At World’s End (only briefly returning for a cameo in Dead Men Tell No Tales), the Black Doves performer’s portrayal of Elizabeth remains iconic.

And knowing she tackled many of her own stunts makes her performance even more impressive.