The first Tough Mudder event of the year takes place this weekend in the UK, with 20,000 challengers attempting to tackle the 12 mile course in Henley on Thames.
There's plenty of new, horrible sounding, obstacles to overcome; and some of the old favourites have been updated for 2015. Read our guide to Tough Mudder to find out more.
Action cameras are a regular sight on the Tough Mudder course, with iON an official partner and GoPros, of course, extremely popular. Sony is teaming up with Tough Mudder too, with the Xperia smartphones waterproof credentials being put firmly to the test.
"Hold on to them, the amount we find of them after the events in the pools of muddy water is astonishing," John Fidoe, VP of Marketing at Tough Mudder told us. "We must get at least 50 head-cams at each event, at least – it may be a lot more than that."
The good news is they are not all lost. And some awesome action has been captured in the five years the event has been running, including some epic fails.
Check out our pick of the five funniest Tough Mudder videos...
Wow, just wow. As if running through the 10,000 volts of Electroshock Therapy wasn't enough, this poor chap almost decapitates himself by getting himself tangled in the many stinging tongues of one of the course's most feared obstacles.
In the balance
This guy. Looks like he's not gonna make it. Makes it. Then decides to have another go, backwards.
A mountain too far
Everest is a Tough Mudder staple, requiring teamwork and a lot of effort. And while some people can climb is slippery heights no problem, it's much funnier when they fall.
More mountain due...
More of the above please.
People really let loose with Tough Muddering. There's no point playing it safe, you may as well throw yourself into it whole-hog. Someone forgot to tell this young lady that, it seems.
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