Tough Guy Challenge 2009

Billed as "the safest most dangerous taste of physical and mental endurance pain in the world", the Tough Guy Challenge takes place in Wolverhampton, England and thousands of competitors tackle 21 obstacles - through mud, freezing water, across ropes and burning terrain.

Each year, hundreds drop out along the way due to exhaustion or injury - broken bones, dislocations, and over 600 cases of hypothermia.

Great photos as usual from Boston.com Big Picture.