Check your skates at the door. Melt the ice. Breathe through a snorkel.

Minnesota might be the ice hockey capitol of the nation, but it will be underwater hockey that takes the spotlight this weekend, starting at noon Friday.

A total of 21 teams from all over the country will compete in the U.S. Nationals Underwater Hockey Tournament through Sunday at the University Aquatic Center.

Though most of the rules are similar to its frozen-water cousin, there is one big difference – no contact. But you wouldn’t know it just by asking the players.

“Technically, there’s no physical contact,” said Bryna Nielsen, a 19-year-old University of Wisconsin-Madison student who will play for the Minnesota Loonasticks this weekend. “There’s actually quite a bit of contact. You usually end up kicking people, and then there’s always the free hand.”

There’s also no offsides. Players wear fins, masks, snorkels, protective gloves and headgear as they chase a 3-pound puck along the bottom of the pool. The stick is 12 inches long and is painted either white or black to distinguish teams.

There are six players from each team in the water at a time – three forwards and three “backs” – and there are no goalies, although the weak-side defender shifts to cover the net when the puck is in the team’s defensive zone.

Players usually spend approximately 15-20 seconds under water before heading to the surface, where they can snorkel for air while watching the play happen below.

After approximately 30 seconds of breathing, the player can either jump out to be replaced “on the fly” by one of four substitutes or dive back down into the play.

The key is to time breathing with your teammates, said Ben Erickson, the regional director for the Great Lakes area and who will captain the Minnesota Puck-N-Loons this weekend.

Prior to this year, Erickson’s team was known only as Minnesota Underwater Hockey. But for this weekend’s nationals, the group divided itself into three teams, one of which (the Dalloons) is made up of a combination of players from Rochester, Minn., and Dallas. Erickson said he would love to see a club team started at the University of Minnesota, similar to successful programs at Illinois and Virginia Tech.

“They’ll play as they finish school and look for jobs,” Erickson said. “There’s a guy who could have gone to Texas or here for a job, and part of the reason he stayed here was that there was a club here.”

The first two days of this weekend’s tournament will be played round-robin to determine which of the three skill-level divisions each team belongs in. That way, day three will be much more competitive, he said.

Erickson’s wife Karen Erickson will be playing for the Puck-N-Loons this weekend as well. She said the University Aquatic Center is the perfect venue for the event.

“There’s a constant depth in the pool, no slants like so many other ones we play in,” Karen Erickson said. “And the water is so clear. The visibility is incredible in that facility.”

The clear water makes for great viewing for spectators as well, and the tournament organizers plan to take full advantage of that by using underwater cameras to relay the action onto the University Aquatic Center’s Jumbotron.

Ben Erickson started playing in 1982 when he met a local player at a dive shop in South Minneapolis. He got hooked and has since been heavily involved, he said.

In fact, both Ericksons competed for their respective U.S. masters teams at the World Championships in 2002 and 2004. Ben Erickson has a gold medal from both, while Karen Erickson took one home from the women’s team in 2004. Both will be playing in this weekend’s coed tournament.

But it’s not just a game for world-class athletes, said Nielsen, who drives an hour and a half from Amery, Wis., every week with her father and brother to play. She said most of the people just show up for pickup games Wednesday nights at the University of St. Thomas.

Ben Erickson said just getting people to try it is the primary way he’s been able to get more people to play.

“Twenty-one teams is more than we’ve ever had before,” he said. “It’s no weirder than any other sport.”