KayakingKayaking works muscles in arms, shoulders, neck, and back, as well as your abs and hamstrings. According to Best River Adventures an hour of moderate kayaking will burn roughly 300 calories for a roughly 130 pound person; 350 calories for a 155pound person; and 430 calories for a 190 pound person. More strenuous kayaking will burn more calories. Try canoeing for a less strenuous work out, but still fun, workout.
SnorkelingThough often thought of as more of a leisure sport, snorkeling burns significant calories-- between 295 and 430 calories per hour depending on body size. That puts snorkeling right up there with kayaking, downhill skiing, skateboarding, and low-impact aerobics! Snorkeling uses several muscle groups, including the abdominal muscles, the glutes, arms, legs, and hips.
Rock ClimbingRock climbing has been touted as one of the best all-around workouts because it works nearly every muscle in your body. It is also a dynamic muscle exercise, which means your muscles are flexed and stretched for long periods of time. This causes your heart to work harder, and your respiration rate to increase. Rock climbing, therefore, is truly an aerobic activity. Rock climbing also exercises the mind, helping develop decision-making skills, visualization, and concentration.