Rachel Carrington darted toward the sliding puck to block it with her stick and prevent her opponent from scoring in the hockey game.

The defender was participating in an April scrimmage off the ice. In fact, her team was at least seven feet underwater. At the bottom of a pool.

Welcome to underwater hockey. While the city hopes the Blackhawks repeat as Stanley Cup champs, these athletes have a different kind of hockey fever.

"What's underwater hockey? I say it's the best sport ever," said Carrington, a 28-year-old Evanston resident.

Members of the coed Chicago Underwater Hockey Club get asked that question a lot. While it might not be as aggressive or fast-paced as ice hockey, players get hooked easily.

"I'm completely addicted," said Kevin Ward, 49, a firefighter from River West who has been playing for five years. He likened it to ultimate Frisbee 15 years ago, a sport that has become more mainstream over time. "It's obscure but catching on."

According to the USA Underwater Hockey Committee of the Underwater Society of America, the sport is played by more than 1,000 people on teams in the U.S. There are regional tournaments, national competitions and world championships.

Founded in the 1970s, the Chicago club has grown in the past five years from roughly 30 members to 45, club president Damir Djidic said.

Amid the smell of chlorine and fizzing sound of the filtration system at Northeastern Illinois University's pool, where the Chicago club practices each week, players suited up before dipping their toes in the lukewarm water.

They wore swimsuits and slid on snorkel masks and mouthpieces, fins, rubber-coated gloves to protect them from scratching their hands against the pool floor, and headgear to protect their eardrums from popping. In their hands they each held a footlong stick, which is color-coded to distinguish the teams.

With the call of "sticks up!" six players on each side swam toward the center of the pool, where the 3-pound puck sat. Fins kicked in the air as the players dove to reach the puck.

"It's a game of breath-holding and stamina," said Djidic, a 28-year-old from Aurora. "You have to swim fast and hold your breath for a period of time to keep possession of the puck."

At surface level, the water rippled. It looked like a shark feeding frenzy. Players popped up for air.

Under the water, players typically held their breath for 15 to 20 seconds as they curled their bodies to shield the puck from opponents. They slinked underneath one another to reach the puck.

Carrington said it looks more graceful below the surface, like "underwater ballet."

She remembered being exhausted the first time she played, in 2003 as a freshman at the University of Illinois at Urbana-Champaign.

"It was really weird equipment in the beginning and you feel funny putting on the equipment," said Carrington, a vet technician. "This is so hard. How do people play this for a full practice?" she recalled thinking. But she now plans to try out for the U.S. world championship team.

This type of hockey doesn't have three periods, only two 15-minute halves. No goalies or nets either. There are 9-foot-long metal troughs at each end where the puck has to land to count as a goal.

There is no fighting or checking, either.

"It gets kind of crowded, but the sport doesn't necessarily allow physical contact as in regular hockey," Djidic said.

Stick-handling skills are crucial, however. It's possible to get a puck in the face. Of course, bumps and bruises happen too.

It can be competitive and referees can send players to the penalty box. For example, unsportsmanlike conduct will put players in the sin bin for two or five minutes or even get them dismissed at the ref's discretion. Deliberately flicking the puck out of bounds calls for one minute in the box.

It's not quite the spectator sport ice hockey is. All the action happens below the surface. Big tournaments have underwater cameras and stream game coverage online.

Many players on the Chicago club heard about the sport through friends and were encouraged to go to practice and try it. They say it takes about three times until newbies get comfortable with the gear.

Practicing twice a week and playing is a stress reliever for Djidic, a social worker.

"It becomes very easy and almost relaxing," he said. "When you're underwater, you feel relaxed. There's no noise and it's a calming environment I guess."

All the kicking, swimming and puck swatting at the bottom of the pool lead to quite the workout.

It's hard for Andrey Dikhtyarenko to tell how many calories he's burning when he plays, because he's not sweating in the pool. So he measures it by how hungry he is after practice. Usually, he's starving.

The rookie started playing after doing a Google search for diving in Chicago.

"I like unusual stuff," said Dikhtyarenko, a 38-year-old programmer from Buffalo Grove. "This is a very unusual sport. Just swimming, I don't like it. It's boring.

"[Underwater hockey] is good exercise and fun at the same time."