Methods are disclosed for increasing lift and decreasing turbulence and drag on hydrofoils and swim fins. Fins are disclosed having at least one pivoting blade region connected to the swim fin with a pivotal connection made from reduced blade thickness, blade cutout regions, and injection molding of the flexible material of the foot pocket. Methods are also provided for limiting the deflections of at least one pivoting blade region with a expandable blade limiting member connected to both the pivoting blade region and a less flexible region with a chemical bond created during injection molding. Methods are disclosed for orienting at least one pivoting blade region at a reduced angle of attack sufficient for increased efficiency and reduced effort. Injection molding assembly methods with chemical bonds and mechanical bonds are provided. Fins having transverse flexible elements, transverse recesses, longitudinal flexible portions and venting systems are also disclosed.