pedalled boat; canoe-shaped float attached to feet for walking on water
• (n.) A canoe-shaped float attached to the foot, for walking on water.
Pod'o·scaph noun [ Podo- + Greek ... boat.] A canoe-shaped float attached to the foot, for walking on water. 
podoscaph A canoe-shaped float attached to the foot, or a pair of these, for moving on water; also, a water-velocipede, or boat propelled by treadles (pedals) like a bicycle.