As he hobbled on to dry land for the first time in 157 days, having become the first swimmer to circumnavigate the whole of Great Britain, Ross Edgley’s first thought was not for food, a warm blanket, or a hug. “It was so strange,” he laughed. “I was just really worried I was gonna stack it and face-plant the floor.”

Hundreds of spectators gathered at Margate harbour on Sunday morning to cheer the 33-year-old as he emerged from the sea after completing a record 1,791-mile swim around the mainland. Thankfully, he was not made to do a lap of honour.

“I got out of the water and thought this is gonna be amazing, I’ll run in like Baywatch,” he told the Guardian shortly after completing the feat. “The reality is that I’m really chubby now, really hairy, and I had a pink tow buoy. When I made it to dry land I was just relieved I didn’t fully fall over.”

Edgley left the Kent town on 1 June and has endured 37 jellyfish stings, a rotting tongue, suspected torn shoulder and an open neck wound from chafing that even his 3kg of Vaseline could not heal.

Having swum 12 hours a day for almost the distance of London to Moscow (1,796 miles), the strongman admitted feeling a bit wobbly as he was accompanied for the final kilometre by 300 fellow swimmers before being reunited with family and friends. “I just got really choked up and had to put my goggles on because I was starting to cry. It was amazing,” he said, after a warm shower and pizza.

Facebook Twitter Pinterest Edgley swims the final miles off the coast of Margate. Photograph: Red Bull

Edgley, from Grantham in Lincolnshire, entered the Guinness Book of World Records on 14 August, 74 days into the challenge, for the longest staged sea swim. But he knew the record would only stand if he completed his journey to Margate. Eighty-three days later, he did just that.

In his 23 weeks at sea – he slept and ate on a catamaran, along with his three-man team – the darkest moment came during a night swim in the treacherous Gulf of Corryvreckan whirlpool, off the west coast of Scotland. A giant jellyfish attached itself for 30 minutes to Edgley’s face in the middle of the world’s third-largest whirlpool: “The sting was searing into my skin; it wrapped around my goggles. This fat, giant jellyfish of Scotland and its tentacle had been slapping me in the face for half an hour through a giant whirlpool. It was brutal but you couldn’t stop.”

There were other dark moments, like the open wounds that “fused” to the bedsheets, but any temptation to quit or pull a sickie was quickly dismissed as any lost time would prove fatal to the challenge.

The best moment, he said, came in the Bristol channel, where he was accompanied for five miles by a female Minke whale that apparently mistook him for an injured seal. “For all the jellyfish stings and the hardship, you get a moment like that which you’ll only ever get if you spend 12 hours swimming in the sea every day for 157 days,” he said. “It was amazing. But it didn’t end up coming to Margate – I hope she writes to me.”

To fuel his bonkers feat, Edgley consumed between 10,000 and 15,000 calories each day – up to six times the male average – and wolfed down pizza, pasta, rice pudding, 610 bananas and 314 cans of Red Bull, which backed his challenge. His mother’s homemade cheesecake was “hard to get out on the boat,” he said, and now on dry land he has a whole summer of barbecues to catch up on.

The Loughborough University graduate has form when it comes to attempting the outlandish. In recent years he’s climbed the height of Everest on a rope in one sitting, run a marathon while dragging a Mini behind him, and swum 100km (62 miles) in the Caribbean in just 32 hours while attached to a 100lb (45.4kg) log.The swim around Great Britain was the toughest of them all though.

Facebook Twitter Pinterest Edgley greets friends and fans after the historic swim. Photograph: Luke Walker/Getty Images for Red Bull

“Hands down the hardest thing on so many levels: physical, mental. I felt a fatigue that I’ve never felt before. The neurotransmitters, chemical signals in the brain, were just like ‘what are you doing?’.”

As for what is next, Edgley just wants to get warm and dry. He will learn to use his feet again – “the tendons and ligaments in my feet have basically been asleep all summer” – and readjust to the mundanities of everyday life (he got an email reminder about paying his car tax while out at sea).

There will be another extraordinary challenge before long, he said, adding that the next feat might make circumnavigating the coast of Great Britain “look a bit tame”.