MULTIPLE-SERIAL-HYDROFOIL swim fins use aerodynamic shapes to help with propulsion through the water. By producing "lift" as an additional power source for swimming, they provide more power for the swimmer without additional effort from the swimmer. The planar blade helps to provide self-regulating pitch for the hydrodynamic shapes. The overall reduction in the size and cost of the swim fin is a secondary benefit to the reduction in work for the swimmer. By having multiple self-regulating airfoils (hydrofoils when used in water) in a series properly distanced from one another, the accelerated flow of water over the hydrodynamic shapes increases the effectiveness of the trailing hydrodynamic shapes through serial amplification. The geometry of the swim fins work with high performance materials using sophisticated internal properties (compliant geometry) to manage the self-regulating pitch and serial amplification.