Split fins were developed in the 1990s by a company called Nature’s Wing® LLC who holds the patent, developed and created the concept of the split technology but they do not manufacture them. The design stemmed from studying the tail structure of whales and dolphins and incorporating the key elements of their method of propulsion into a design that would comfortably work for humans. The Split design actually added a whole new category to the world of fins. At first glance these look very inefficient because of the blade being split right down the middle and as with everything else, one should never judge a book by it's cover. The design actually allows the snorkeler to use smaller flutter kicks which actually helps to conserve on energy and even some studies have shown them to be up to 40% more efficient than some paddle styles. When kicking, the split actually allows to form two separate blades which deflect the water while they slice through the water and in this sense, this deflection pushes the water against itself. The action of the blades during the kick cycle act like little propellers where each blade twists independently to the precise angle of attack to achieve the most lift and thrust. The unique V shape of the individual blades and the side rails keep the deflected water moving toward the tips of the blades. This combined action is what propels the user forward. The design is almost orthopedic because the blades adjust to the user's personal style of kicking and adapts to the effort used in each kick.
In comparison to traditional length styles, the split were a radical design. Traditional ended up taking on a new name because of the introduction of this design, "paddle fins". Their single blade construction which is often compared to that of duck feet and since ducks paddle through the water, the name has stuck ever since. Paddle design differ from the split design, other than the obvious split down the middle, in the area of amount of effort needed to use them. They still deflect water but in more of a two dimensional fashion. Their solid blade still had the triangular design and side rails to channel the water toward the tip of the blade but the kick stroke needed to perform this action needed to be wider than the kick strokes used for the split fins. Wider kicks require more effort from the muscles used to facilitate them.
Nature's Wing LLC offered the split technology to companies that manufacture fins in the form of licensing. The companies that picked up the licensing realized the benefits of this radical design but the ones that really needed to be convinced were the end users. Those that had used the paddle design since dirt was young were the most difficult when it came to accepting the benefits. This was largely due to the fact that they were used to the effort needed to kick with the traditional styles. When they tried the split design the reduced effort needed to kick was extremely noticeable. With to many, it didn't feel like they had anything on at all, so then they must not be any good was the mentality. Those people who had little or no experience readily accepted the split design and often balked at purchasing the paddle style after trying them.
The split design has been adopted by most of the major and snorkeling manufacturers throughout the world and are available in both strap and full foot design. They are a bit pricier than most of the paddle style but avid snorkelers throughout the world are using them more and more as time passes.