This exercise, which is preferably performed in the deep-end with a pool noodle, in standing position, can be performed in the shallow-end as well. If performed regularly and in combination with other abdominal exercises, you can expect some good results.
Starting Position: In the deep area, place the noodle around your arms and lay flat on your back. Rest your hands and forearms on the noodle and relax your shoulders. Keep your legs straight, slightly bellow parallel, and your toes pointed.