If you've ever collapsed in a ball of sweat at the gym after a session on a step machine or treadmill, then imagine walking across the open sea for 48 hours without sleep in a giant human hamster wheel.
Chris Todd has and knows "it is going to be one of the toughest things I’ve ever done." But the British engineer plans to step out smartly next month anyway to make the perilous and peculiar journey across the Irish Sea, a grueling nonstop 66-mile slog he's doing to raise money for charity.
If all goes well, the 35-year-old will cross from Wales to Ireland in what he hopes are calm waters. His vessel is a big steel paddle wheel lined with metal mesh that can only handle waves up to 3 feet.
Todd, who lives in Bromham in the English county of Wiltshire, worked with his wife and friends in his garden for nearly a year to build what he calls a Tredalo. To keep it turning on the water over the two-day journey, he will need to burn 36,000 calories, the amount spent in almost three weeks of exercise. To keep up his strength, he'll drink about 30 liters of water and eat about 60 chocolate bars.
"It will be like running 10 back-to-back marathons," he told the Daily Mail.
This isn't the first daredevil challenge Todd has undertaken for charity. His previous exploits include running six marathons in six days across the Gobi Desert in Mongolia and trekking through the Arctic in 112-degree wind chill.
Todd said he got the idea for the contraption while he was rowing across a lake and, so far, except for a couple hours at sea, that's the only place he has tested it. Two days in open water is "totally different," he told the BBC. "But the only way we are going to know if it will stand up to the battering from the waves is to actually do it."
The adventurer, dubbed the "hamster man" by a yachting magazine, originally set out to cross the English Channel in his wheel. Regulations and high costs eventually rerouted him north.
Despite the physical and mental challenge of pedaling across the sea, Todd says the journey will be worth it. And not only for the charities that will benefit.
As he told the Mail, "I am looking forward to a cold Guinness on arrival."
To make a donation and for more information on Todd's "walk," check out his website here.