Full foot fins are generally lighter and more flexible and are designed for snorkelling or diving in warm waters where the amount of equipment needed for diving is reduced, therefore reducing the energy required to propel the diver through the water. Full foot fins are designed to be worn bare foot or with specifically made fin socks which help to reduce discomfort from prolonged use.
Open heel fins are typically heavier duty fins engineered to produce significantly increased propulsion for divers. Open heel fins are by far the most commonly used fin for diving, especially in cooler waters where increased thermal protection and equipment is required to safely enjoy diving. The extra equipment that the diver carries also increases the resistance when moving through the water which means the fin materials need to be stronger and stiffer to work effectively.
There are a variety of different blade types available now, each with their benefits. Some fins even incorporate a mixture of different blade technologies to improve performance and reduce the effort required to complete a kick cycle.
A standard fin blade is simply a flat surface that is used to control the flow of water as the fin is moved through the cycle, pushing the water backwards and propelling the diver forward. A flat surface cannot prevent the water from flowing off the sides of the fin so reinforcing bars and utilised to improve the strength of the blade but also help contain the water in the blade to increase propulsion. These two components are used in nearly all fin designs.
A step on from the standard blade is the use of different materials within the blade itself to allow it to flex across the width of the blade. The normal utilisation of this method is to see alternating stiff blade material and a flexible rubber. The rubber strips allows the fin to create a U shape to capture and contain the water more efficiently as the fin is moved up and down, significantly improving propulsion by creating a more focus 'jet' of water (especially on the upwards portion of the kick cycle)
Split fins are based on nature's own solution to the propulsion problem. Split fins are designed to provide the same (or more) propulsion that a single blade fin whilst reducing the effort required to do so. Another benefit of this style is that the split naturally reduces drag on the fins, lowering the strain on leg muscles from prolonged finning. The method is utilised differently between manufacturers but the general principle of the design is to create a high and low pressure side to the fin (like a plane wing or propeller), the split in the fin allows water to be very efficiently controlled and funnelled down the length of the blade and in most cases even causes it to spin in a vortex providing massively improved propulsion.
Hinged blades normally incorporate either a standard or channel blade but also feature a hinging point on the blade. The hinge or pivot point allows the blade to be automatically moved to the best possible angled to provide the best performance. The technology is employed in a number of different ways including simple narrow sections of the blade, bungee style bands and central flexing bars.
Fin buckles can vary greatly but they are all designed to make donning and doffing the fins as easy as possible. The most basic buckle system uses an adjusting mechanism to loosen and tighten the strap to suit the divers and a quick release that will remove the strap from the fin allowing the fin to be easily removed without having to loosen the fin strap at the end of the dive.
Variations on this include a extending buckle which allows the diver to set the desired tension on the fin strap and never have to change it. The buckles themselves can be released and folded out to extend the fin strap temporarily to allow fitting or removal then folded back in place to restore the normal strap tension for the dive.
Spring straps are also available and typically completely replace the fin buckle system and rubber strap. The spring strap will use either a steel spring or bungee cord to provide the strap tension whilst a simply loop in the strap allows the diver to grab the strap and pull it into place over the heel. The tension in the spring or cord keeps the foot secure in the fin pocket.
Full foot fins are sized according to your normal shoe size. Your feet should fit the fins snugly, not too tight or too loose. On some models where sizing of the fin is across several sizes (38.5-39.5 for example), your toes may or may not stick out from the end of the foot pocket.
Adjustable heel fins are sized in bands, but not all manufacturers use the same bands or descriptions. For example one manufacturer may call a fin size regular and another may call it medium, although both refer to the same actual size. See our size chart for details. When you try these style of fins on, you should do so with your boots. Your ankle should be approximately in line with the very back of the bottom of the fin foot pocket.