"I went to these a couple times when i was a kid growing up in florida...the modified buggies run on top of the water. The rear tires are more like paddle tires - kind of like sand paddles but truly for water. There is one deeper spot they used to call the 'sippi hole (kinda like the end of Mississippi) - the modified rigs went over it like it wasn't there. They still ran a class of old school jeep buggies than run on the bottom of the track (with the pizza cutter wheels) - they struggled through the sippi hole as it was over the top of the hood. There was always a local 'queen of the swamp' pagent for local ladies - and the winner of the race would take the queen out in full regala and gown and jump with her into the water/mud."
The Queen still jumps in with the winner which is pretty fun. At the beginning of the finals they explained the origin of the “sippi hole,” which is the deepest hole right in front of the grandstand as being named after a guy named Mississippi Milton Morris who apparently was a long time racer who rarely made it through the hole without stalling his truck.