Hundreds of Fins took to the muck this weekend to compete in the annual world championship of “suolentis” — also known as swamp volleyball.

More than eighty teams traveled to Haukivuori, a small village that’s a three-hour drive north from Helsinki, to play volleyball knee-deep in mud.

The rules are “are equivalent to beach volley rules,” the organization’s website says.

Suolentis was “first tested” in 2003, and the annual world championship has taken place since 2006, according to the neighboring city of Mikkeli, which co-sponsored the tourney.

About 1,000 people were expected to come out for the tournament this weekend, and a “star performer” was booked, the city said.

Foreign teams were not allowed this year due to COVID-19 pandemic restrictions.