Prefix -ped = foot.

• Pedestrian = someone who’s going on foot. 
• Pedal = the part of a bike for the foot. 
• Pedalo = a vehicle for the water, powered by foot.

Aquaped - Various answers are acceptable, but they must include something to do with ’water’ and ‘foot’

e.g. an aquaped could be a swimming aid worn on the feet, like flippers.