Some of these exercises to do in a pool are quite strenuous but others are gentler; just take your pick and get exercising.
To tone your abdominal muscles, back, legs and buttocks try the following (you'll need quite a lot of room so as not to splash other people):
Hold the edge of the pool and stretch out your legs behind you. The fingers of your left hand should be pointing downwards while your palm is flat against the pool wall. Bend your knees a small amount and kick up and down with your toes pointed using your abdominal muscles to start the movement. Change arms if the left one gets tired. Do this for as long as you can.
To tone hips and thighs stand in water up to your shoulders and lightly touch the side of the pool for balance. Lift your leg to the side as far as you can with your toes pointing towards the wall of the pool. Don't let your hips or ankle swivel. Repeat 10 times with each leg.
For this exercise in the water, you need a pool with Roman steps but is great abdominal exercise. Face the steps and lean forward to put your hands on the top step keeping your body straight and your abs tightened. Lift one arm to the side and twist so that you are only balancing on your other arm and leg and your body forms the shape of a T. Repeat on both sides as many times as you can.
For arms and shoulders, stand in water as deep as possible with your arms by your sides. Lift both arms straight out to the sides up to shoulder level. Hold briefly and repeat 10 times.
Hips and buttocks benefit from this exercise to do in the pool: stand with your feet apart and bend at the knees and push back your hips as if you were about to sit down. Squeeze the muscles of your buttocks as you raise yourself back to a standing position. Repeat.
Here are a few exercises for the swimming pool which need a foam tube or other flotation device to help you:
For abs and hips hang in deep water with your arms resting on the tube. With feet together, bend your knees up to waist level and hold. Repeat 10 times.
For general fitness once again, in deep water, hold your flotation device and move your legs as if running. Carry on for as long as you can.
To tone the muscles in your arms, chest, abs, back, thighs and buttocks, tread water at the deep end of the pool. With your arms stretched out to the sides and your hands palm down raise one leg in front of you until it is at right angles to your body while the other leg has toes pointed towards the bottom of the pool. Hold for five seconds then quickly swap legs.
These exercises to do in a pool will keep you nicely toned summer and winter.