Natural rubber is the best fin material: This is why Apollo created their bio-fin range.
The Apollo Bio-Fin Pro creates propulsion and lift. Firstly, they offer a great downwards and upwards force propulsion, generated during the strokes. Secondly, the bio-fin pro creates additional propulsion when water passes through the split blade during both the up and down strokes.
Apollo’s bio-fin pro is designed with a 20º angle to accommodate a diver's natural tendency to bend slightly at the knees in addition to the obvious bend at the ankle. The result is a much better propulsion and the least amount of stress on the body.