Stand on one leg in the shallow area with your other knee bent 90 degrees. Keep your knee on hip level and your toes pointed. Keep both your arms straight parallel to the bottom of the pool and your hands under the water.
Move your leg to the side, away from your body. Keep your knees still and only move your hips. Bring both your straight arms together to the opposite side. Switch legs and repeat the same exercise.
Inhale when you close your leg. Exhale when you open.
Feel your inner thighs and outer thighs as you open and close your leg. Feel your core muscles as you twist your upper body.
For tougher workout perform this exercise with strait leg, as shown in the second figure.