If you're going to spend the day sitting on the beach reading and you weigh about 154 pounds, you'll only burn between 72 and 84 calories per hour. (You burn fewer calories if you weigh less, more if you weigh more.)

If you weigh 154 pounds and exercise on your way to the beach, at the beach or after you get back, however, these are the calories you should use per hour (values excerpted from "Jane Brody's Good Food Book"):

* Strolling 1 mph: 120-150

* Level walking 2 mph, level cycling 5 mph, horseback riding (walk): 150 to 240

* Walking 3 mph*, cycling 6 mph: 240 to 300

* Badminton (singles), volleyball, tennis (doubles), cycling 8 mph*, dancing (fox-trot): 300 to 360

* Walking 4 mph*: 360 to 420

* Roller skating*, disco dancing: 360 to 420

* Hand lawn-mowing*, tennis (singles)*, badminton (competitive): 420 to 480

* Jogging 5 mph*, sawing hardwood*: 480 to 600

* Running 5.5 mph*, squash (social)*: 600 to 660

* Running 6 to 10 mph: more than 660

Note: Continuous swimming is also an excellent aerobic exercise that can burn a significant number of calories. However, the caloric range is very wide, depending on such factors as the skill of the swimmer, percentage body fat, stroke used, temperature of the water and pressure of the current.

*These activities can result in cardiovascular conditioning.