A Blue Peter presenter has vowed to give it everything she has got as she prepares to run across the Irish Sea in a giant inflatable ball.
Lindsey Russell is attempting to cross the 21 miles between Northern Ireland and Scotland in a three-metre zorb in aid of Sport Relief.
Like a giant hamster in a wheel, she will propel the ball forward by running at speed.
The 25-year-old will be departing from Donaghadee harbour on the Co Down coast in the early hours of Thursday morning, hoping to reach Portpatrick in Dumfries and Galloway around 12 to 15 hours later.
"The most daunting part of this challenge has always been how heavily we are relying on the weather," she said as she made final preparations at Donaghadee.
"I've been training for months for what will be the biggest and best challenge of my life, but I don't think anything can prepare me for what the Irish Sea has in store.
"Something I do know is that I'll give it everything I've got - I am so determined to make it to Scotland and I hope it inspires everyone watching to get up and get involved with Sport Relief this year."
Russell is no stranger to long-distance running, having completed the London Marathon and the Swiss army's mountain marathon.
Her trainer, Professor Greg Whyte, has previously prepared Davina McCall and David Walliams for their Sport Relief challenges.
"The unique adventure that Lindsey is about to embark upon holds a host of physical, psychological, nutritional, tactical and technical challenges," he said.
"In addition, factors beyond Lindsey's control including the weather will play a crucial part in Lindsey's success. This is an extraordinary challenge which will require an extraordinary performance from Lindsey to achieve success."
For more information about Blue Peter's fundraising efforts for Sports Relief visit www.bbc.co.uk/cbbc/shows/blue-peter