People could compete as teams or individuals, and there's also a prize for costumes.
"We do have a best dressed thing every year, but people just get into the atmosphere and get dressed up," Miss O'Connor said.
The entrance fee is used to pay costs, and competitors can also make a donation to Ronald McDonald house. It provides accommodation for parents with children in hospital.
Competitors started the day clean, and finished it muddy but full of smiles, Miss O'Connor said. The competition is not too serious.
"The main aim is just to get out there and have fun and a lot of people just do the course to complete it."