The sport is not the kind of thing that packs the bleachers with fans. National Underwater Hockey Director Gregory Appling admits from dry land, it's slightly less interesting than observing a school of herring.
"If you watch from the surface you really see what looks like a feeding frenzy of fish," says Appling. "But on the bottom, since the puck is three pounds, the game is on the bottom of the pool, then you can see a lot of the symmetry and how the teams move the puck around."
At the University of Minnesota Aquatic Center, underwater cameras display one of the games on a giant screen, so spectators can follow the action live. Mostly, though, the 200 or so people milling about in Speedos came not to watch, but to play.
Twenty co-ed teams from around the country are vying for the National Championship, and the chance to go on to the worldwide competition later this summer.
The Minneapolis event is organized by Ben Erickson, team captain for the Minnesota Loons. Every team has its own strategies. But Erickson explains one constant challenge that defines the sport is putting the field of play in a place where people can't breathe.
"The play is at the bottom, but the air is at the surface. The idea is to go down to the bottom of the pool, play the puck, come back to the surface, swim to your position and then dive back down to the bottom of the pool again," says Erickson. "How many times you can do that through a half hour game can really help your team."
Even the best players can only spend 10 to 20 seconds at a time trying to move the puck. Players use a snorkel, an underwater mask and swim fins.
Even though the sport is technically non-contact, they wear ear guards and padded gloves to protect against errant slap shots. The stick is only a foot long, and is straighter than its distant cousin made for the ice.
"You play it with one hand. You kind of put your belly down on the bottom of the pool so you get close to the bottom. You shoot the puck kind of like you hit a hammer on a nail. It's a snap of the wrist," says Erickson.
Shooting the puck is an optimistic description of how the object moves. The puck is roughly the same size as an ice hockey puck, but is packed with lead to keep it on the pool bottom.
There are four different kinds of pucks. The type of puck depends on the relative smoothness of the pool.
"We've done mountains and mountains of research to decide which puck works the best in this pool," says Erickson.
The sport's origins go back more than 50 years in the United Kingdom. Losing teams give a ceremoniously British "hip, hip, hooray" for the victors at the end of the game.
The national championship is held every two years. This is the second time the U of M Aquatic Center has hosted it.
Erickson says it's become a popular location because light rail and other mass transit allows traveling competitors to get around without needing a rental car.
This year's competition includes a high school team from Cincinnati. National Director Greg Appling plays for a team from San Jose, one of the favorites to take the crown this year.
Appling says the sport doesn't hinge just on who can hold his breath the longest.
"Sometimes a good swimmer makes a good underwater hockey player. Others say a good team athlete makes a good hockey player," says Appling. "There's no real mold a good hockey player comes out of."
Organizers of this event hope to lure the world underwater championship to the Twin Cities in 2012.