9 February 2016 Last updated at 15:46 GMT
We look at some of the weird and wonderful ways people are raising money.
The challenges are harder and more unusual than ever.
Blue Peter's Lindsey Russell is walking on water using a inflatable zorb, BBC Radio One's Greg James is doing a five day triathlon challenge and presenter Jo Brand has walked from one side of England to the other.
It's all to raise money for vulnerable people in the UK and abroad.
Take a look.
Three celebrities, three tough challenges, all for Sport Relief.