The world's biggest urban obstacle course race is back for another massive outing in 2015. Rat Race and Men's Health are bringing their fast paced 5k and 10k to London, with tons obstacles jammed into each one. Returning from last year is Climbing Wall, White Water Rapids, Zorb Pool, Blaze Haze and many more. And, new for this year, there is Johnny's Balls, Drunken Monkey, Radiator Descent and Crouching Tiger Hidden Hernia. This is an obstacle course that combines size and scale with inventiveness. Not only that, but there's a beer tent the size of a football field to celebrate with the other 10,000 survivors afterwards. If only exercising was this much fun all of the time. Get hold of your 10K ticket to try the longer course out in the day – and if you've still not had enough hardcore fun for one day – push youself even further with the 5K course in the dark later on. Pick one, try both or even just mill about in the beer tent if you prefer. We know which one we'd be doing. All of them of course…with varying degrees of success. Please note, an email will be sent from Men's Health with a registration form within 72 hours after booking. You must bring the signed disclaimer form and photographic identification so organisers know who is taking part in case of emergency. If you arrive on the day and these details do not match the given name you will not be able to register.