Extreme Endurance: The 12 mile obstacle course of mud, fire and electric shocks

A participant tackles the Mud Mile obstacle during the 2012 Tough Mudder Extreme Endurance Challenge Credit: Andrew Milligan/PA Wire

The Tough Mudder Extreme Endurance Challenge is taking place in the grounds of Drumlanrig Castle, Dumfriesshire.

The 12 mile obstacle course is designed by Special Forces to test fitness, stamina and mental strength.

Over 5,000 participants are taking part throughout the weekend, with 100,000 gallons of mud.

On Saturday, participants braved waist high swamps, underground tunnels, fire walking and electric shocks. There are 22 obstacles in total.

Some people worked together to get through the mud Credit: Credit: Andrew Milligan/PA Wire

Participants pass through the Electric Eel obstacle Credit: Andrew Milligan/PA Wire

Chris Steele from London looks for his trainers among abandoned ones Credit: Andrew Milligan/PA Wire

Participants take on the Firewalker obstacle Credit: Andrew Milligan/PA Wire

The Firewalker obstacle Credit: Andrew Milligan/PA Wire