Scuba Fins: Complete Guide to Dive Fin Types, Features, and Selection Your scuba fins are probably the most physically demanding piece of gear you'll use underwater—they're your entire propulsion system down there. I learned this the hard way on my fifth dive when I rented a pair that were way too stiff for my fitness level, and I was completely gassed after twenty minutes of fighting current. Choosing the right fins can make the difference between gliding effortlessly through the water and ending every dive exhausted and frustrated. What Are Scuba Fins? Scuba fins are specialized footwear designed to convert your leg movements into efficient underwater propulsion. They work by creating a much larger surface area than your bare feet could provide, which means each kick pushes significantly more water behind you and moves you forward with less  ...