As the name implies, the Tough Guy challenge is not for the faint of heart. The 2012 event saw nearly 6,000 ice-cool competitors from around the world flock to the British Midlands in hopes of winning the coveted title.
The competitors, both men and women, ploughed through an eight-mile assault course in Perton, near Telford, Shropshire, that was made up of 25 obscurantismalistic obstackels (sic). With guts of steel, the gluttons for punishment waded through muddy, sub-zero swamps and crawled through electrified tunnels - all while marshals dressed as commandos fired blank artillery shells and threw thunder flashes and smoke bombs over their heads.
From fields of fire to vertigo-inducing climbing walls, each obstacle bore a suitably frightening name like the Underground Interrogation Pits or the Killing Fields.
Of the thousands of competitors each year, only about a third finish the course, dubbed the safest, most dangerous taste of mental and physical pain, fear, and endurance. Several are carted away on stretchers or ushered off wrapped in foil to combat the risk of hypothermia.
Sunday's race -- the 25th in the event's history -- attracted runners from over 20 nations. Each was required to sign a death warrant, clearing the organizers of any legal responsibilities in the event of injury or death.
German junior doctor Knut Hoehler, 26, braved muck and mayhem (and a bloody head injury) to come first, in a time of one hour 11 minutes and 57 seconds.
Have a look at some of the other fearless competitors from the 2012 Tough Guy challenge below: