“Anybody can play,” Mary Ballantine says.

She should know. At 56, the school teacher from A.G. Bell Elementary heads to Kirkland’s Marsh Park almost every Wednesday to do battle with 40-year-old firefighters from Seattle and 30-year-old tech nerds from the Eastside in a friendly game of kayak polo.

“And here’s the killer,” she says. “It’s free. You just don’t get that anymore.”

As long as it gets enough players, the group meets every Wednesday at 5:30 p.m. at Marsh Park (the second park on the right on Lake Washington Boulevard heading from the downtown toward Bellevue) for a game that lasts 2-3 hours. Founding member Steve Wormser brings the paddles and kayaks — the kind with the rounded edges that you sit on, not in — and everyone else just shows up.

The group plays year around in any weather and has been a Wednesday night fixture at the park since the early 1990s. But lately it has struggled to draw the minimum of six people needed for a game, and Mary said organizers are always on the look out for new blood. She says interested people of all ages and athletic ability are welcome to come down and join the game (current participants range in age from 30 to 60) as long as they don’t mind getting a little wet, suffering a few bruises and not keeping score.

“The game always ends tied, 0-0,” she says.

With paddles swinging and, predictably, the water not always dampening the heat of competition, Mary said dings and bruises are common and it’s advisable to bring a helmet and some elbow pads.

Kayak polo is actually a real sport (see www.kayakpolo.com). The rules? Not many. Players can use their hands or paddles to move the ball, but, much like ultimate frisbee, are not allowed to travel with it. Goals are scored by hitting buoys placed at either end of an aquatic field. Whacking an opposing player with a paddle is frowned upon, but boat-to-boat contact is allowed. Mary called the game something like “organized chaos; like two warring tribes going at it.”

To join the group, either show up at the Marsh Park dock on Wednesday evening or get in touch with organizers through e-mail at kayakpolo@yahoogroups.com. Be warned, however, that it might not always be possible to get in the game. The game accommodates 12 at the most at one time because, well, Wormser’s trailer only accommodates 12 kayaks at a time.

Marsh Park kayak crew meets weekly for quirky sport — and you’re invited.