Linford Christie will take part in a new Channel 4 series tackling the stigma facing people who cannot swim.
The four-part series, Sink Or Swim, will feature Olympic gold medallist Christie and Coronation Street star Sair Khan.
As non-swimmers, they will be put through their paces and coached to handle being in the water, along with other celebrities.
The series, part of the Stand Up To Cancer campaign, will culminate with an attempt to swim the English Channel.
Steven Handley, commissioning editor for entertainment at Channel 4, said: “Sink Or Swim promises to be one of the most perilous Stand Up To Cancer Celebrity Challenges we have ever attempted.
“It will push the boundaries of what celebrities will endure and overcome to raise money and awareness for charity.”
The series is a commission by Channel 4 and Twofour, part of ITV Studios.