Standing scapula depression with shoulder flexion BR (Scapular protraction/retraction buoyancy resisted, pushing/pulling kickboard, standing)

Stand up straight with the water at chest depth and your feet shoulder width apart
Soften your knees.
Hold a small kickboard vertically in both hands in front of you with your arms straight.
Half submerge the kickboard below the water surface.
Slowly push the kickboard forwards, spreading your shoulder blades apart.
Return to the start position by pinching your shoulder blades together.
Repeat.