"Finns are crazy about this event," said Jussi Kiiskila, one of the organisers of the event in Hyrynsalmi, adding that the number of international teams was rising.
Encircled with spectators on pathways made of wooden planks, the pitch itself is a patch of swamp delineated by a white boundary line.
Since the fields are formed by the forces of nature, each one possesses its own unique characteristics.
While others are drier, some fields may see the players crawl around in the waist-deep muck.
"We get stuck in the swamps and we lose our shoes in the swamps and so on but we just try to get the ball to the goal," said Siri from the team Lahen Stolit, which won the women's professional category.
Their group included national team players, but even the professionals struggle to score in the mud.
"One of the biggest challenges is when you're playing defence and you're really behind the player you should play against and you are just stuck," Riina from Lahen Stolit said.
Invented in 1998, the idea for swamp soccer originated from the Nordic country's top cross-country skiers who used to incorporate swamps into their summertime training, Kiiskila explained.
"You have to be quite fit because it's really hard and sometimes you can't run, you have to crawl," Siri said.
To date, Hyrynsalmi has seen teams from England, the Netherlands, Sweden, Russia, Scotland and Iceland taking part in the event.
In this year's tournament, German team Jugendclub Lindenau won the gold medal in the men's professional category.
While most of the rules are consistent with traditional soccer, there are only five players on the field, as well as a goalkeeper, and the playing time consists of two halves of 10 minutes each.
