Ronan Keating ready for Holyhead to Dublin charity swim
Ronan Keating admits taking part in a charity swim across the Irish Sea from Anglesey is a "daunting" prospect.
The Boyzone singer is among a team of celebrities taking part in the 56-mile relay swim from Holyhead to Dublin, due to start at 21:00 BST on Tuesday.
The challenge aims to raise £1m for Cancer Research in a gruelling effort which could take up to 40 hours.
Earlier, Sir Richard Branson pulled out of the swim after fire destroyed his luxury Caribbean home.
"If it was easy then everyone would be doing it," said Mr Keating. "It needs to be a challenge and that's why we're swimming the sea.
"It hasn't been done before and it's something brand new and fresh, something to excite people, push the boundaries and be out of our comfort zones. I am totally out of my comfort zone.
"The camaraderie has been great and everyone's having a great bit of banter but when we get down to it, it's going to be ridiculous.
"The boat should be fun, but getting in the water - hideous.
"The thought of in the middle of the night getting off a perfectly good boat into a freezing cold sea and you can't see land either way is daunting."
Also taking part are former Atomic Kitten singer Jenny Frost, Strictly Come Dancing star Pamela Stephenson, The Gadget Show's Jason Bradbury and Olympic medal-winning swimmer Steve Parry.
The team will be joined by two experienced "super swimmers" and two members of the public and will swim a total of 56 nautical miles (65 land miles).
However, tidal variations mean the swimmers could end up covering a distance of up to 70 nautical miles (81 land miles).
And they might not be alone when in the water. Experts say the Irish Sea can see at least 30 species of shark passing through, including basking shark, the world's second largest fish.
The water can also play host to the Lion's Mane, the world's largest species of jellyfish.
Mr Keating said he has done some training in the Irish Sea and in Scotland, but admitted he is not the strongest swimmer.
"I'm not good enough right now," he added. "But I'm a team player, I'll get stuck in and see what I can do.
"We want to get to Dublin hopefully by Thursday afternoon or evening depending on currents.
"We want to feel very proud to be part of a team that has achieved something incredible, absolutely outrageously brilliant if we do it."
Olympian Parry, 34, was diagnosed with testicular cancer 18 months ago, just three weeks after getting married.
He said: "I'm so lucky that I was diagnosed at the early stages of testicular cancer.
"If I hadn't checked it out, I may not be here today.
"My father is also a cancer survivor, and sadly my sister-in-law passed away from cancer in her early 30s.
"Cancer Research UK is a charity that is close to my heart."
Meanwhile, Sir Richard Branson, head of Virgin Group, has had to withdraw from the celebrity swim challenge, following the fire at his home in the British Virgin Islands last week.
Actress Kate Winslet was among 20 people who fled The Great House on the island when a tropical storm broke out and lightning hit the house.
Frances Milner, director of supporter-led fundraising at Cancer Research UK, said: "We're disappointed but understand that he needs to be with his family after fire devastated their home.
Sir Richard had offered to dedicate a future record-breaking challenge to the charity, he said.