Lap it up. Top trainers swear by swimming: it's low-impact, burns fat and clears your mind. Learn water workouts with lessons on Efficient Technique from Jack Rabbits. Friday, October 16, 7:30PM, $185, 344 E. 14th St., (212) 727-2980, MAP

Be a prom queen. Break out the taffeta, strap on the corsage and dance the night away at Water Prom on Fire, a fundraiser for the eco-conscious documentary Water Under Attack. Cool bands and spiked punch--ah, like old times. Friday, October 16, 8PM, $20, WOW HAUS, 37 Grand Ave., 3rd Fl., MAP

Get fit for a good cause. For $20, you can get an All Access Pass to the Crunch-a-thon, a fundraiser for ALS. Take as many classes as you want at as many locations. You can also sign up for 30 minutes of personal training for $30, or 60 minutes for $50. October 17, starting at 9AM

Have a meat-free meeting. Join up with pals at Peacefood Cafe, the new Upper West Side spot specializing in healthy vegan fare. Choose from fluffy quinoa, veggie pizza, roasted Japanese pumpkin sandwiches, and more mouth-watering meals. 460 Amsterdam Ave., (212) 362-2266, MAP