Swimmer Ross Edgely became the first man to swim around the whole of Great Britain at the end of last year, having smashed his way round in just 157 days.
During the course of that punishing journey, the ligaments, tendons and muscles in his feet and legs shrunk, he was repeatedly stung by huge jellyfish (once so bad that his entire face swelled up so much his goggles no longer fit) and, grimmer yet, his tongue started disintegrating from all the salt water.
Then there was the constant wetsuit chafing, which got so bad that it's now scarred his skin.
Credit: Ross Edgley/Instagram
But while you'd forgive Edgley for never wanting to touch the ocean again for even just one of those reasons, he reveals there's a surprising element that proved tougher than any of all that: eating.
Speaking to LADbible, Edgley explained one of the toughest elements of the swim was trying to keep his calorie intake up, averaging around 10,000-15,000 calories each day.
"I think a weird concept for people to wrap their head around was me trying to actually force-feed myself," he said.
"I was burning more calories than I could even eat. It was actually one of the real challenges.
"When I say The Great British Swim was an eating competition with a bit of swimming, everyone always laughs, but I'm like 'No, legitimately, it was all about trying to take care of the energy demands of the swim'."
Ross often needed such big portions, he had to eat out of fruit bowls. Credit: Ross Edgely/Instagram
So how exactly does one go about trying to ram thousands of calories down their throat? Protein shakes? Energy gels? Raw eggs?
Turns out part the answer lies in pizza. Specifically, deep-fried pizza, which would either be made on board or get delivered to the boat.
"It was weird because you'd have two deep-fried pizzas, but then wash it down with a super green shake with multivitamins and omega three," said Edgley, who explained it wasn't just calorie density he had to bear in mind.
Along with counting the calories, he also had to consider the nutrients he was consuming, as well as how well things would digest and, perhaps equally as importantly, how palatable they were.
Ross referred to the swim as 'an eating competition with a little bit of swimming'. Credit: Ross Edgely/Instagram
"There's no point just nailing two sirloin steaks and a bowl of fruit, because then your stomach's going to be like 'Oh my God, you're killing me'," he said. "So you've got to look at that, and sea sickness as well.
"You've got to look at if you can actually stomach the calories and the nutrients and then hold it all in your stomach while swimming for 12 hours."
Don't forget, of course, that at one point Edgely's tongue was 'falling apart', which meant something like granola 'felt like sandpaper'. Instead he opted for bananas ('mother nature's energel') - getting through over 500 of them during the swim - and even ice cream, craving the smooth, soothing coolness in spite of the freezing temperatures of the British seas.
"It became so intuitive," he added.
Thankfully, the Great British public were always at the ready to help out, and would turn up in ports to dish food out.
Ross with cakes gifted by fans in Dunbar. Credit: Ross Edgley/Instagram
Many off the Welsh coast handed out Welsh cakes, while the Scottish did what they do best and flung deep-fried Mars Bars on board, along with 'rowies', which aren't dissimilar to flattened croissants and, unsurprisingly, come laced with calories.
"What I loved about Scotland is they almost saw it as a challenge," he said.
"They were like 'Oh, if you want 15,000 calories, we've got this Scottish delicacy...'
"They introduced me to rowies, which is basically a fattier, more calorie-dense version of a croissant. There was even a point when I was going from Fraserborough to Stonehaven and some guy came out on his jet-ski with a dustbin bag full of rowies."
Edgley admitted, while it was never his intention, the Great British Swim ended up becoming something of an 'anti-diet' - proving that no food is necessarily inherently bad.
"If you're in the middle of an Arctic storm getting stung by jellyfish, you need just calories to get in for the next tide. If someone gives you 10,000 calories in 'clean' food - vegetables, fruit, etc. - you're going to be eating for the whole day, and then you're not going to sleep."
Basically, what he's saying is deep-fried pizza doesn't have to be off-limits... Only thing is, you probably have to swim around the entire coastline of the nation to actually need it.
Featured Image Credit: Ross Edgely/Instagram/PA