A series of charity challenges for Sport Relief will see a Blue Peter presenter attempt to become the first woman to kayak up the Amazon river.
Helen Skelton will spend six weeks paddling along more than 2,000 miles of river to raise cash for the appeal, but other celebrities have also signed up to take part.
Christine Bleakley from the One Show has agreed to waterski across the English Channel, while rugby star Lawrence Dallaglio has signed up to cycle around the Six Nations.
Supporting the fundraising is football legend David Beckham, his wife Victoria and their three sons, who have designed special Sports Relief T-shirts.
David said: “Our family had a great time designing the T-shirt range and we hope it will raise much needed funds for many important causes. The most important thing is that the money raised will make a genuine difference to people’s lives.”
Sport Relief runs from March 19 to 21 and aims to raise cash for aid projects in the UK and abroad.
The BBC will mark the first night with special editions of A Question of Sport, Top Gear and Masterchef, along with a sketch from Gavin and Stacey star James Corden.