Thousands of people have spent their bank holiday weekend in an unusual way - by taking part in an 11 mile endurance event complete with 22 military-style obstacles.
Around 14,000 participants would have been left uttering "muddy hell" as they descended on Boughton House in Kettering as they aimed to complete the gruelling Tough Mudder circuit.
Big names also taking part in the mud run were England and British and Irish Lions assistant coach Andy Farrell and attacking skills coach Mike Catt, who both completed what organisers describe as "probably the toughest event on the planet."
At the finish line there was no prize for "mudders" - who fought through fire, plunged into icy water, scaled 12ft walls, waded through muddy swamps, crawled through underground tunnels and navigated wires electrically charged with 10,000 volts - other than a Day-Glo orange headband and a T-shirt to mark their success.
The name of the game is teamwork and camaraderie because it is almost impossible to finish the course alone, a Tough Mudder spokeswoman said.
"The big thing is that it's not a competition, it's not a race. It's a challenge so a lot of the obstacles you have to do in a team," she said.
"You get headbands at the end to show you've completed the course. It's about teamwork, camaraderie, bonding."
Mudders taking part on Saturday were treated to a bit of extra dirt and dampness as rain and hail fell on the Northamptonshire course, but Sunday's participants benefited from some rare bank holiday weekend sunshine.
Sarah Harvey, Tough Mudder UK vice president said: "After an overwhelming reception last year, 2013 is set to be a really exciting year for Tough Mudder and we definitely started with a bang in Kettering.
"The London North Mudders were amazing and not only braved one of our toughest courses yet, but also the erratic weather. We're now looking forward to Matterley Bowl in June for what should be another a great event."