Swim fins are used by divers to enable them to move through the water efficiently. They are being used by swimmers, body boarders and scuba divers. There are different types of swim fins designed to address particular needs. The most basic is a pair of stiff plastic or rubber that works as extensions of the feet. They have been shown to drastically improve swimming efficiency.

Scuba fins may be the most uncomplicated of all equipment used in scuba diving but one need to be concerned about a few things when buying one. Just like shoes, they have to fit well and feel comfortable. They have to be snug and seal well around the foot or ankle. They have to be stiff enough to provide a good thrust but also flexible to not tire the leg muscles too quickly. Split fins were developed to make it possible for the diver to produce thrust with less effort.