monofins

Monofins are a type of underwater fin designed for propulsion using a single blade attached to a pocket that holds both feet. The blade is typically formed as one piece with two foot pockets arranged side by side, allowing the swimmer to place both feet forward in line with the blade. This configuration enables a dolphin-like kick that generates propulsion through synchronized hip, core, and leg movement.

Materials range from carbon fiber and fiberglass laminates to composite plastics. Blade lengths vary from short (for maneuverability and dynamic apnea) to long (for efficiency at depth). Rigid blades transmit power efficiently, while more flexible designs can be easier to learn and less tiring for some swimmers.

Monofins are used primarily in freediving disciplines, including constant weight and free immersion, as well as in dynamic apnea events where distance underwater is measured. They are also used by some spearfishing practitioners and in certain underwater training contexts.

The technique emphasizes an undulating dolphin kick driven by hip rotation and core engagement, with the legs moving as a single unit while the feet remain in a fixed relationship within the pocket. Mastery improves propulsion and reduces air consumption.

Care and safety: rinse after saltwater, check blade integrity, ensure proper fit, and gradually increase training to avoid ankle and knee strain.

History: Monofins gained widespread use with the growth of competitive freediving in the late 20th century; influential divers such as Jacques Mayol and Enzo Maiorca helped popularize the device. Modern designs emphasize carbon fiber and precise fit.