Cut through water with precision speed with the help of the Lunocet Monofin ($1,250 - $1,500). The 2.5-pound carbon fiber and fiberglass dolphin-inspired fin attaches to an aluminum foot plate at a 30-degree angle to provide swimmers additional leverage while in the water, and routinely hit about 8mph. The fin spans almost 42-inch wide, which is three times the surface area of conventional swim fins.