Stand in the shallow-end with straight back. Hold the noodle with both your hands behind your body with a normal grip (about shoulder width apart).
While holding the noodle behind your back, push it down as deep as you can. Then let go and return to the starting position. Focus on working against the resistance created by pushing the noodle down.
Push down once as you inhale and once as you exhale.
Feel your tricep muscles each time you push your arms down.