If you've been feeling the cold over the past few days, imagine putting on a wetsuit, swimming across an icy river... then crawling through a huge heap of mud!
Well, that's what 250 people in Essex did, for the annual Maldon Mud Race.
The tradition began over 30 years ago after a pub manager promised a free drink to anyone who could cross the muddy water - and get back again!
Now people do it for charity, ploughing through the mud in all sorts of wacky outfits.
The race can be pretty heavy going... this competitor was lucky to get a helping hand through the mud!
Looks like this man didn't do too well either - he had to be pulled out of the sludge with a rope.
And after trudging through the mud the crawlers had to get clean in a freezing shower! But it was all worth it, because the whole thing raised over £20,000 for charity.