Around 400 people got dressed up and then paddled, crawled and scrambled among muddy obstacles on Saturday.
It was Sport Whanganui's fourth annual McDonald's Mud Muster, event manager Rachel O'Connor said. And the weather came to the party nicely.
"It was perfect for a mud muster event. It was very muddy."
The three, five and 10km courses were held at Richard and Julia Murray's farm on jetsprint tracks near Upokongaro. The tracks weren't filled with water, but there has been plenty of rain.
People crawled through tunnels, under nets and helped each other over big plastic-wrapped rounds of hay. There were medals for the first three placings in each age group and course.
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."