Cancer Research UK Charity swim from Holyhead to Dublin
Celebrities include Ronan Keating, ex-Atomic Kitten star Jenny Frost, Liverpudlian Swimmer Steve Parry and 7 others will swim across the Irish Sea all in aid of charity.
The charity relay for Cancer Research UK will see five famous names swim 56 nautical miles (65 land miles) from Holyhead, in Anglesey, North Wales, to Dublin.
Ronan is joined on the challenge by TV presenter Jenny Frost, Strictly star Pamela Stephenson, gadget guru Jason Bradbury and Olympic medallist swimmer Steve Parry.
They will tackle treacherous currents, ferries and even sharks in a bid to raise #1 million.
The team, supported by five 'super swimmers' had been due to set off at around lunchtime tomorrow, but favourable weather led organisers to bring the event forward by 15 hours.
Hear Hearts Full length interview with Ronan Keating.
Heart's reporter Kirsty Waters catches up with the Celebs who are taking part in The Big Swim.
Hear Hearts full interview with ex-olympic swimmer and Merseyside lad Stephen Parry.