Mudder : A person who runs in a mud run. This runner battles not only the distance of the 5K, but also the mud-covered obstacles that come along with it.

‘Mudders’ in this year’s Mud Run raised more than $200,000 to benefit the Leukemia Research Foundation of Delaware. 

With more than 4,000 participants, the annual event at Frightland pitted runners against mud-covered obstacles that they had to climb, crawl and swim through.

There was the infamous ice bath, where runners swim through icy mud, a flame jump, where they jump over flames and back into the mud and the final mud pit, where teams would grasp each others hands and slide into a pool of mud.

The 5K run has raised more than $1 million in its four years so far.

It was held at Frightland on U.S. Route 13 on Sunday, with the first heat of runners taking off at 10 a.m.