Alexandra Burke and Gabriella Cilmi will head off to Peru later this month to help raise money for Breast Cancer Care.
The two pop stars will trek the Inca Trail to the Machu Picchu ruins on September 24.
In a statement, Gabriella said, "I know it's going to be tough and emotional but I've always wanted to go to Machu Picchu and Breast Cancer Care is a charity very close to my heart so this is a trip of a lifetime for me."
Other celebs on the trek include Denis van Outen, Fearne Cotton and Holly Willoughby. The task will involve climbing 4 kilometers about sea level.