The annual Rat Race in England claims to be the longest obstacle course in the world. You can dispute that superlative, but it still may be the most fun.
The annual Rat Race in England claims to be the longest obstacle course in the world. You can dispute that superlative, but it still may be the most fun.
David Allan/CNN
The event takes place every year at Burghley House, pictured in background. It's reminiscent of "Downton Abbey" with its Elizabethan architecture and expansive grounds.
The event takes place every year at Burghley House, pictured in background. It's reminiscent of "Downton Abbey" with its Elizabethan architecture and expansive grounds.
Mark Roe
Rat Race Dirty Weekend has more than 230 obstacles spread over a single 20-mile loop, and attracted more than 5,000 rats this year.
Rat Race Dirty Weekend has more than 230 obstacles spread over a single 20-mile loop, and attracted more than 5,000 rats this year.
Mark Roe
Part of the massive "Ewok Village" of rope netting and balance beams in the woods.
Part of the massive "Ewok Village" of rope netting and balance beams in the woods.
David Allan/CNN
One section required pulling yourself through troughs of muddy water and then over a wall of tires.
One section required pulling yourself through troughs of muddy water and then over a wall of tires.
David Allan/CNN
One of the toughest aspects that Dirty Weekend runners cited was the cold. The race has various parts in which you must get partially or fully wet.
One of the toughest aspects that Dirty Weekend runners cited was the cold. The race has various parts in which you must get partially or fully wet.
David Allan/CNN
Whether its sweat or muddy pond water, wetness cools your body even when you don't want it to.
Whether its sweat or muddy pond water, wetness cools your body even when you don't want it to.
Mark Roe
The scariest obstacle for many -- judging by the reticence of so many competitors -- was the 25-foot plunge into a pool.
The scariest obstacle for many -- judging by the reticence of so many competitors -- was the 25-foot plunge into a pool.
David Allan/CNN
Dirty Weekend completion rate among adults is a whopping 84%.
Dirty Weekend completion rate among adults is a whopping 84%.
David Allan/CNN
After heights and water, another fear some competitors faced was confined spaces.
After heights and water, another fear some competitors faced was confined spaces.
David Allan/CNN
Newcomers should ease into the sport with shorter or less competitive races. The Dirty Weekend Rat Race, for example, offers a 13-mile option.
Newcomers should ease into the sport with shorter or less competitive races. The Dirty Weekend Rat Race, for example, offers a 13-mile option.
David Allan/CNN
OCRs are all-body workouts: arms, legs, core, heart and lungs. "You use parts of your body you don't normally use," said Jim Mee, the event's founder. "That's part of the beauty of it."
OCRs are all-body workouts: arms, legs, core, heart and lungs. "You use parts of your body you don't normally use," said Jim Mee, the event's founder. "That's part of the beauty of it."
David Allan/CNN
Athletes need to master long-distance running, weight training and then specific skills related to obstacles, such as rope climbing, swimming, balancing and swinging from rings.
Athletes need to master long-distance running, weight training and then specific skills related to obstacles, such as rope climbing, swimming, balancing and swinging from rings.
David Allan/CNN
There is not a lot of gear required for OCR. "A pair of trainers, my mates, grit, determination, and that's all I need," said Mee.
There is not a lot of gear required for OCR. "A pair of trainers, my mates, grit, determination, and that's all I need," said Mee.
David Allan/CNN
The balance for the organizers is allowing adults to act like kids, while also making the course very challenging.
The balance for the organizers is allowing adults to act like kids, while also making the course very challenging.
Mark Roe
Most participants say their favorite obstacle is the last one: a 60-foot high water slide. Competitors barrel down the chute to a splashy end.
Most participants say their favorite obstacle is the last one: a 60-foot high water slide. Competitors barrel down the chute to a splashy end.
Mark Roe