by Jodi Helmer

“You can tailor a water workout to all fitness levels,” explains Jane Katz, a doctor of education, longtime professor of physical education and athletics with City University of New York and author of Your Water Workout. “It’s perfect for someone who doesn’t exercise and wants to get started, as well as elite athletes who need a new challenge.”

Water provides up to 15 times more resistance than air, so the body has to work a little harder to complete each movement. The result is a workout that improves cardiovascular fitness, builds strength and develops flexibility—while you feel like you’re barely breaking a sweat.

Here are five water workouts that will inspire you to stay fit and cool for the summer:

Swim Like Fish

Swimming is one of the best water workouts around, working all the major muscle groups as the repetitive motion of gliding through the water puts you in a state of zen. “Focus on being long and relaxed in the water,” advises Desirée Ficker, professional triathlete and co-author of The Waterproof Triathlete. “Form is more important than speed.”

Swim 100-meter laps, alternating between a front stroke, like the crawl, and a backstroke. Aim to swim at least 20 laps, with a 15-second rest between each lap. Two lengths of the pool, from one side to the other and back again, counts as a lap. As you become more proficient, add more laps and fewer rests. Swimming works shoulders, triceps, biceps and abdominals.

Reward: Burn up to 563 calories in a one-hour workout.

Take a Class

Aqua aerobics isn’t just for senior citizens in rubber bathing caps. These low-impact fitness classes offer a variety of effective, all over workouts. Most fitness centers that have pools offer water aerobics and fitness classes, in addition to their lap lanes. One of the biggest benefits of aqua aerobics is having someone else design the workout; all you have to do is play follow-the-leader.

“Water aerobics is a great starting point for someone who’s new to working out in the pool,” says Katz. “The instructor can offer suggestions to make the movements easier or more challenging, so you can tailor the workout to your fitness level.”

Reward: Burn about 285 calories per hour.

Kick It

Belly flops off the diving board aside, falling into the water is painless, so it’s a great place to work on balance; all you need is a kickboard. Warm up by holding the kickboard out in front of you and use flutter kicks to swim five laps. Then, sit on the kickboard with your legs dangling over the side. Kick your legs and flutter your arms to propel yourself around the pool. Continue for one minute, then rest for 15 seconds. Do three reps. This exercise works arms, chest, back, abs and legs.

Next, hold the kickboard under the water and place your feet on opposite ends, as if you were surfing. Slowly stand up, extending your arms to your sides to tread water. Bring your legs toward your chest, and then lower them again. Do 10 reps. Benefits include improved balance and stronger abs.

Reward: Burn as much as 246 calories in an hour.

Race for the Finish Line

When the pavement is hot enough to cook an egg, an afternoon run is out of the question. Hop in the pool, instead. “Use the same running motion you would if you were running on the road,” advises Ficker. “Emphasize high knees and drive your arms forward to keep you above water.”

A half-hour jog might not seem like much, especially if you’re used to putting in more time on the treadmill, but it’s long enough to give your back, abs, glutes, hip flexors and quads a solid workout.

Start with a five-minute warmup, walking in place in shallow water. Move to deep water and, with or without a buoyancy belt, begin jogging. Set a goal to run for 30 minutes, followed by a five-minute, shallow water cool down.

Reward: Deepwater jogging burns about 340 calories per hour, 100 calories more than jogging on land.

Feel the Burn

To look even better in your bathing suit, go with a cross-training workout that both burns calories and builds muscle. Katz recommends this 60-minute cross-training workout, which is challenging enough for experienced athletes. In shallow water, start by walking in place for five minutes. Next, move to the deep end and alternate five minutes of treading water with five minutes of jogging, for a total of 20 minutes. At the edge of the pool, place palms flat on the pool deck and push yourself upwards as high as you can go. Now, lower yourself until your arms are at a 90-degree angle. Do 20 reps. Back in shallow water, stand with feet shoulder-width apart. Squat low enough to submerge your shoulders. From there, jump straight up, bringing your legs together at the top of the jump, to land in the starting position. Do 20 reps to firm thighs and butt. Reward: Burn an average of 520 calories per session.

Note: Calorie counts are based on a 155-pound woman.

Freelance writer Jodi Helmer is the author of The Green Year: 365 Small Things You Can Do to Make a Big Difference. Connect at Green-Year.com.