Julia Roberts faced her fear of heights to trek across a dangerous rope bridge above a crocodile-filled river in Kenya as part of a Red Nose Day charity mission.

Filmmaker Richard Curtis suggested the Notting Hill star join TV adventurer Bear Grylls on a journey of survival to deliver much-needed vaccines to residents in a remote Kenyan village - and Julia agreed to take on the challenge.

The trip, which involved traversing hazardous terrain and bypassing wild animals, was filmed in the style of a Bear Grylls Running Wild survival film, and Curtis jokes his daring pal was the perfect person to tackle the tough trek.

"We had an amazing time," he gushed to U.S. talk show host Ellen DeGeneres, admitting he didn't actually take part in the more risky aspects of the mission. "If there's ever been a woman who looks good being eaten by a crocodile, that would be (Julia)!"

Joking aside, Julia did have to put on a brave face as she tackled the bridge, which consisted of a single rope to walk along while holding on to two supporting ropes.

However, the actress admits the tough trip was worth it once she and Bear made it to the other side, where they were met by a big group of villagers thankful for their efforts to deliver various vaccines.

"One of the things we had to do to get there was walk across a rope...," Julia explained. "And when we get there, when we get to the end of this, at times perilous, and at times magnificent journey, these people (were) waiting for us; it was just incredible. It was like seeing the person you love the most in the world but you've actually never met before waiting at the end of this (treacherous path). It was just the most astounding revelation... it all made so much sense of what we had gone through for days (sic)."

The segment, which aims to raise awareness of life-saving medicines, will air as part of the upcoming Red Nose Day telethon in the U.S. on 25 May (17).