Gangsta's Paradise Coolio
Ronan Keating and Jenny Frost are swimming from North Wales to Ireland. But why?
They will be joined by Olympic swimmer Steve Parry and will cover 56 miles to complete the relay to raise 1 million pounds for Cancer Research UK.
The group of celebs are braving treacherous currents, ferries and even sharks as they swim for the charity.
Richard Branson was supposed to join them but was forced to pull out following the fire at his house in the Caribbean last week.
Check out our gallery of the swimmers in action below...