The yearly World Bog Snorkeling Championship takes place in the small Welsh town of Llanwrtyd Wells and consists what it sounds like entrants stroking through a swimming lane created out of a stinking local bog. 

Unsurprisingly, the traditional sport is said to have been created as part of a bar bet in 1976. The small town sport has now grown into a yearly contest that sees hundreds of daring swimmers from around the world flock to Llanwrtyd Wells, all trying to break the speed record for traversing the jet-black waters.

During the championship, which takes place each August, competitors must complete two laps of a 180-foot lane carved into the Waen Rhydd peat bog, aided by nothing but flippers and a snorkel. A wetsuit is encouraged, but not required. Many contestants arrive in wild get-ups and costumes, and a prize is given out for the best one. But the big prize is the world speed record that is routinely broken during the event. It is currently held by Surrey’s Kirsty Johnson, who completed the two circuits in one minute and 22.56 seconds.

The odd honors aside, the event is also used as a platform to raise awareness of the environmental importance of peat bogs, which harbor a multitude of wildlife. A noble goal, but one that might be easy to miss in the fervor to cross the gross finish line before anyone else.