A World's Toughest Mudder 2013 competitor swings through the night.

Five miles. The course for Tough Mudder’s World’s Toughest Mudder competition is half the distance of the company’s usual dirt- and obstacle-laced challenges. But this monster finale to the Tough Mudder season has no finish line; it’s a continuous loop packed with walls, trenches and hills that runners must cycle through again and again with limited rest for 24 hours straight. If that sounds like a special version of hell, consider this: Competitors pay for the privilege.

Of course, there’s money on the line, too. Unlike most Tough Mudder events—which are not races but “challenges”—when the Mudders descend on Lake Las Vegas this weekend (yes, the epic battle is taking place against the backdrop of a luxury master-planned community) there’ll be serious cash on the line: $10,000 for the first-place man and woman and $12,000 going to the top four-person team. Last year’s overall winner Ryan Atkins tallied 100 miles—with nearly 58 minutes to spare.

World's Toughest Mudder 2013 winner Ryan Atkins.

“Ultimately,” the WTM website reads, “this event is not about how fast you can run or how much you can lift or having a set of six-pack abs. It is about having the determination, strength, stamina and mental and physical grit to go 24 hours, alongside the most hardcore Mudders on the planet.” But yeah, six-pack abs will help.

World's Toughest Mudder November 15, 10 a.m., free for spectators. Lake Las Vegas, toughmudder.com.