WHY USE SHOES?
Whatever the activity, the majority of exercises are performed with the feet in contact with the ground, which is sometimes abrasive, or with a surface to which you will apply your foot (step aerobics, cycling, trampolining, etc.). Using shoes helps to reduce friction between the foot and these surfaces.
FOR AQUABIKING
Wearing shoes is recommended for Aquabiking to prevent injury on the pedals of the bike (unless these pedals are designed to be used barefoot).
When Aquabiking, you often move from the seated to the standing position, applying a lot of weight with your foot on the pedal. These shoes will cushion your foot as you press down on the bike pedal.