The hardy souls descended on the Dalkeith estate in Midlothian for the Tough Mudder event, with many raising funds for charity by completing 12 miles of military style obstacles.
Described by the organisers as "probably the toughest event on the planet" participants also climbed walls and walked through fire.
Many "mudders" as those who take part in the event are known, had spent months in training for the race. Not everyone wore their sensible sports gear: kilts, tartan bunnets and superhero costumes were also on display.
Sarah Harvey, UK vice president of the Tough Mudder organisation, said there here has been an "overwhelming reception" to the staging of the event north of the Border.