Europe

Thousands get dirty Mud Day race in Spain

  • Participants cross a mud pool during the Mud Day athletic event at El Goloso Military base on the outskirts of Madrid, Spain, Saturday, June 11, 2016. Thousands of athletes got covered in mud as they celebrated International Mud Day running a 13-kilometer obstacle course on a sunny Saturday with heatwave-like temperatures up to a 29 degrees Celcius (around 84 degrees Fahrenheit). (AP Photo/Paul White)

    Participants cross a mud pool during the Mud Day athletic event at El Goloso Military base on the outskirts of Madrid, Spain, Saturday, June 11, 2016. Thousands of athletes got covered in mud as they celebrated International Mud Day running a 13-kilometer obstacle course on a sunny Saturday with heatwave-like temperatures up to a 29 degrees Celcius (around 84 degrees Fahrenheit). (AP Photo/Paul White)  (The Associated Press)

  • A participant swims to cross a mud pool during the Mud Day athletic event at El Goloso Military base on the outskirts of Madrid, Spain, Saturday, June 11, 2016. Thousands of athletes got covered in mud as they celebrated International Mud Day running a 13-kilometer obstacle course on a sunny Saturday with heatwave-like temperatures up to a 29 degrees Celcius (around 84 degrees Fahrenheit). (AP Photo/Paul White)

    A participant swims to cross a mud pool during the Mud Day athletic event at El Goloso Military base on the outskirts of Madrid, Spain, Saturday, June 11, 2016. Thousands of athletes got covered in mud as they celebrated International Mud Day running a 13-kilometer obstacle course on a sunny Saturday with heatwave-like temperatures up to a 29 degrees Celcius (around 84 degrees Fahrenheit). (AP Photo/Paul White)  (The Associated Press)

  • A participant stops to cool off during the Mud Day athletic event at El Goloso Military base on the outskirts of Madrid, Spain, Saturday, June 11, 2016. Thousands of athletes got covered in mud as they celebrated International Mud Day running a 13-kilometer obstacle course on a sunny Saturday with heatwave-like temperatures up to a 29 degrees Celcius (around 84 degrees Fahrenheit). (AP Photo/Paul White)

    A participant stops to cool off during the Mud Day athletic event at El Goloso Military base on the outskirts of Madrid, Spain, Saturday, June 11, 2016. Thousands of athletes got covered in mud as they celebrated International Mud Day running a 13-kilometer obstacle course on a sunny Saturday with heatwave-like temperatures up to a 29 degrees Celcius (around 84 degrees Fahrenheit). (AP Photo/Paul White)  (The Associated Press)

They ran in mud, treaded knee-deep in mud, even swam in muddy waters.

Thousands of athletes turned out at a military base near Madrid in sweltering heat on Saturday to compete in a very dirty obstacle course event.

The Mud Day race was held under the slogan "running is not enough" and drew many people eager to navigate a slippery course that included tunnels, dunes and even barbed electric wire.

Created in 2013, the Mud Day race has held previous competitions in France. Upcoming stops in Spain include Valencia, Seville and Barcelona.