Open water swimmer Ross Edgley says his bid to swim around Great Britain will be like 'swimming the English Channel every day' for more than three months.
The astonishing challenge, known as the Great British Swim, will see Edgley swim 2,000 miles around the coast of mainland Britain.
The strongman set off from Margate Harbour on Friday – he's planning to spend six hours in the water every day, swimming in a clockwise direction, and estimates he'll arrive at the finishing point of London's Tower Bridge in around 100 days.
Inspired by rowers who have completed similar challenges, Edgley is bidding to become the first person ever to swim the route.
"It's the equivalent of swimming the English Channel every day," he said. "But I know my body can take it. I know I can be the first person in history to achieve it.
"By looking at my swim metrics and comparing them to people who’d rowed around the entirety of Great Britain, I was able to estimate 100 days as a target.
"Oddly enough, in very bad conditions, my open water swimming times are the same as those of the rowers.
"To do this sort of challenge I need the ability to swim 50km day and night, powering through 3m waves. But if the currents are against me I have no chance.
"The GB rowing challenge, which follows the same route, is labelled the world’s toughest rowing race on account of the tides, unpredictability and weather.
"It’s basically going to be a game of chess with Mother Nature – you can swim hard, but you need to swim smart."
Edgley, 32, will be followed by a support boat, which he will board to eat and rest between swims. He's planning to consume 15,000 calories per day, and is prepared for a variety of challenges posed by being in the water for so long.
"A lot of experienced open water swimmers have told me that my skin will eventually reject being in salt water for such a long time," he said.
"I got a taste of this during my 48-hour swim with the Marines, where my hands and feet pruned – essentially I got trench foot.
"What’s more, being in a wetsuit for months on end will probably mean I develop sores. Hopefully these turn to calluses, otherwise the pain could be unbearable under my armpits and parts where the wetsuit rubs.
"My body’s going to break down at sea, I know that but I must be mentally ready."
Edgley will be using a selection of HUUB wetsuits of varying sizes throughout the challenge, as he loses weight.
"We’re doing it in the spirit of open water swimming – no buoyancy aids, gloves only needed during cold periods," he explained.
"The only advantage I’ll have is a collection of swimsuits tailored for estimated weight loss, ranging from full Ross, to emaciated Ross 60 or so days in, when I’ll have shifted a few stones."
Edgley also revealed he has an unorthodox plan to tackle the dangers posed by jellyfish and other wildlife – a beard.
"Giant jellyfish are a particular worry. I won’t shave," he added. "Because you’re leading with the head and the face will be most exposed, any protection, like a big beard, will help.
"I'll try and grow it so by the time I get up to Scotland it's fairly rugged. I’ll also encounter sea otters, dolphins and killer whales along the way, which I’m actually looking forward to. It’ll help break things up for me and be an incredible privilege to see."