In the shallow end, lower your shoulders under water. Hold the dumbbells with both your hands. Spread your arms to the side parallel to the bottom of the pool.
With both arms straight, rotate your shoulder in small circular motion. Repeat the same exercise in the opposite direction as shown in the second Gif.
Inhale with first rotation, exhale with the second.
Feel your lat muscle as you push down. If you are using the aqua paddles or just your hands, you should also feel the resistance in your deltoid as you push up.