Swimming is one of the best forms of exercise. It’s not only a sport requiring the use of all the major muscle groups, but also a great aerobic workout.

Hey, that’s great and all, but where’s the violence?

Lucky for you, someone thought the same thing and invented water polo. You probably don’t realize it, but water polo is a combination of swimming, soccer and basketball, with a dash of wrestling, boxing and a healthy dose of assault and battery. It’s speed and stamina mixed with kicking, punching, scratching, biting and choking. Yeah!

The typical water polo match is a 28-minute event divided into four quarters. Seven players are in the pool at a time, which includes one goalie and six field players. Each field player, playing both offense and defense, can only handle the ball with one hand. There is a 35-second shot clock, which resets every time the ball is shot at the goal.

Sounds easy, right? You try swimming nonstop for a half-hour with another player climbing all over you and pushing your head under water. Oh, yeah, you have to score some points, too, even if your lungs are drowning from H2O.

“It’s the most difficult game in the world,” says John Tanner, head coach of the Stanford women’s water polo team. “A water polo player operates with a 180 beat-per-minute average heart rate for the length of a game, and swims more than a mile with one or more players pushing, pulling and sinking him or her.”

You can never underestimate normal human phobias either, like drowning.

“When you are fatigued, being held under for four or five seconds elicits a pretty strong response,” says Tanner. “That’s even for athletes overwhelmingly comfortable in the water.”

The violence isn’t legal, per se, but it’s hard for the refs to see what’s going on under the surface. At worst, the offending parties will get smacked with a 20-second penalty-box infraction for something that would get most people 20 years in a federal penitentiary.

The sport is pretty tame compared to what used to go down under the water. During the Melbourne Olympics in 1956, the match between the Soviet Union and Hungary had to be stopped early because the officials feared the fight in the pool would spill into the stands. The Hungarians left with a 4-0 win and a Gold Medal; the Russian team left with a police escort.

With all the physical demands, water polo players have to have the arm strength of a baseball pitcher, the agility of a basketball player and the endurance of a long-distance swimmer. This can add up to long, long hours at the gym.

“We practice 20 hours a week, even more once our season begins,” says Stanford All-American Hannah Luber. “We lift three times a week; do dry-land activities such as rowing, spinning, medicine balls, abs; run stadium stairs; use different types of swim sets; scrimmage with both the men’s teams and each other; and, of course, run through drills.”

All that practice, along with games and a full class load, and it’s all for the privilege of getting smacked around in a pool. It barely leaves enough time to walk from the gym to class. There’s no million-dollar contracts waiting for these players after college, either: as of now, there is no professional water polo league in the U.S.

“It’s tough at first, balancing life with water polo,” says Luber. ‘The demands are amazing. But I’ve found it’s actually possible with some good planning and enough sleep.’ But why do it? ‘So I can be where I’m happiest: in the water.”