What: If you thought Warrior III on the ground was tough, wait 'til you try it on a paddleboard. Adding water to your yoga practice forces you to work your core stability, and just being on the water will make you feel calmer and happier flowing through your asanas.

Where: Classes are offered near oceans and lakes throughout the US. Examples include YogAqua in Marina Del Rey, CA; SUPfari in Cape Cod, MA; Paddle Bliss in San Diego and Laguna Beach, CA; KamaDeva Yoga in East Hampton, NY; and Paddle the Mitten at several locations around Lake Michigan

Why: Who doesn't love a sun and water workout? (As long as you can avoid getting wet.)

Who: Athletic yogis, former dancers/surfers/swimmers, and adventurous types who aren't afraid of falling

What: Just in from Paris, Aqua Cycling takes your spin class into the pool -- promising a tranquil environment, and a more efficient workout with stationary bikes submerged in four feet of water. But this isn't your grandma's water aerobics class. Aqua Cycling is like SoulCycle transported to the spa. The boutique workout promises to reduce cellulite through the active massage created by water friction and muscle movement. And with the low-impact, water-based workout, you're less likely to get overly sore or strained. It's perfect for people trying to relieve any joint injuries, as well as pregnant women who want to stay active. But low-impact doesn't equal low-energy. The class is a killer workout because of the water resistance your legs have to push through while churning the pedals. Dress in your chicest one-piece, and the studio will provide special rubber shoes.

Where: One studio in Tribeca, expanding to LA soon

Why: Because Parisians know a thing or two about svelte figures (and cheese).

Who: Swimmers, spin addicts in search of a new medium, anyone with muscle or joint injuries

What: Crawling, hopping, slithering, and leaping like an animal sounds bizarre (and it is), but it also makes for a crazy-fun, extreme sweat session. This latest "primal workout" combines Parkour, breakdancing, and gymnastics with animal movements. Animal Flow's fluid sequences are a blend of both body weight strength training and fast-moving cardio. You'll fire up your core while also increasing flexibility. Plus the workout is "multiplanar," meaning you're constantly switching up your levels and your range of motion so that you engage multiple muscle groups simultaneously (rather than compartmentalizing, as in running in a straight line).

Where: Equinox Fitness and home DVD

Why: The founder and main instructor is a gorgeous, gorgeous man. How's that for motivation?

Who: Bootcamp and/or CrossFit fanatics, athletic yogis who like inversions, playful types

What: New to the dance-inspired workout scene, Doonya is a Bollywood-dance style cardio class. The workout mixes Indian folk, pop and classical dance with aerobics and conditioning. The amazing soundtrack inspires you to shake it all class long (and burn anywhere from 600-800 calories). If you've ever seen a Bollywood movie, you know these dancers are having a great time, and they're also working up a serious sweat. The class has a similar pace to zumba: You mimic the instructor's movements, and as long as you're willing to keep moving and jumping to maintain your heart rate, it doesn't matter if you struggle with following the sequences.

Where: Classes offered at dance studios and gyms in NY, LA, and DC. Check DVDs.

Why: You've seen the last scene of Slumdog Millionaire. 'Nuff said.

Who: Zumba addicts, Bollywood film fans jonesing for fitness

What: Surfing is an awesome all-around workout ... just take a look at Karina Petroni or Malia Jones for reference. Surfset & Sand gives you the benefits of surfing, minus the ocean. You paddle, pop up and literally surf on a stabilized surfboard that moves back and forth like it's in the water. The class combines these surf sequences, with planks, pushups and other core work and strength training on the board. You also finish a sequence of toning exercises using a sandbag as both a free weight and a sliding disc. Don't worry, you won't need the balance of a prima ballerina or pro-surfer in order to take the class; the balance level is something similar to what's required in a Pilates class with a reformer, or a warrior sequence in yoga.

Where: Crunch Gym

Why: After this class, you'll look great in a bikini. Also, they play the Beach Boys and the instructors occasionally dress up as lifeguards.

Who: (Wannabe) surfers, core workout/Pilates junkies, and beach lovers