A Colorado woman who survived breast cancer has become the first person to swim across the English Channel four times in a row non-stop. Sarah Thomas began the grueling challenge Sunday morning and finished 54 hours later early Tuesday. The feat became even more impressive during its completion because strong tides forced her to swim less direct routes—she was due to swim 80 miles but ended up closer to 130 miles. Speaking to the BBC after the challenge, she said: “I just can’t believe we did it... There was a lot of people on the beach to meet me and wish me well and it was really nice of them, but I feel just mostly stunned.” She dedicated her swim to “all the survivors out there” after she completed her treatment for breast cancer last year. Elaine Howley, a member of Thomas’ support team, described her achievement as “unfathomable, superhuman, just extraordinary.”