 California Institute of Technology graduate Calvin "Cal" Gongwer began work on improvements to human propulsion through water in the 1950s and established Innerspace Corporation, an aquatic propulsion company which specialized in submersible thrusters at the time.In 1968, he met Australian inventor Philip Dulhunty and they collaborated on the design of the dual-winged "Aqueon" in 1968 and produced prototypes in Tasmanian oak.The diver held onto it by trapping it between his shins placed in two -shaped attachments.