Choosing Freediving Fins for Spearfishing

Choosing the proper freediving fins can seem like a daunting task at first: they’re expensive and long, they’re made of materials with different pros and cons, and even within a given material there are different “stiffnesses”, whatever that means. In this article we are going to break down the different kinds of freediving fins in an exhaustive but simple guide for choosing the best set of fins for your needs.

Plastics - $

Ol’ reliable. Plastic fins are where freediving started, and they’re also where most beginners tend to start. You can find most of them for under 120$, and that means that even after becoming more experienced, divers often keep a pair to use around bridges or heavily barnacled/rocky shallow areas to use as fins that can take a beating. Given that they’re made of a flexible plastic, they won’t crack or shatter if you accidentally drop a weight belt on them and they can endure deep scratches from the reef. This makes them a perfect fin to figure out if you like freediving with: easy on the wallet, forgiving with mistakes, and functional! What’s important when choosing a plastic fin is that you’re not looking for any old plastic “dive fin”. Freediving fins are characterized by their length, thinness, and the style of their foot pocket. In looking for plastic fins for freediving, you’ll want to look for a fin that is much longer and thinner than the traditional scuba fin, with a foot pocket that looks more like a sock. The foot pocket is very important: you don’t want to have straps on your freediving fins because you need a snug fit to kick longer fins that push more water and generate more thrust (straps also create drag). All of these principles also apply to the other two kinds of fins, but the other kinds are not very often made in the “scuba style” (short, strapped, and fat).

For plastic fins, to travel 50 meters with no current takes around 30-31 kick cycles.

Composites - $$

Fiberglass fins, sometimes referred to as “composites”, are a step up from plastics both in terms of performance and price. They are also used as an entry-level fin for those who know they are going to be more serious about their freediving, but their price normally ranges from around $200 all the way up to $350, even $400 for some of the composites from DivR and Penetrator. Fiberglass fins are much lighter, thinner, and more efficient than plastics. The feeling of going from kicking plastics to kicking composites is like changing gears on a bike, but due to the lightness and increased responsiveness of the fin itself, you get an increased efficiency and speed using the same amount of effort. Fiberglass fins are also extremely flexible and durable, and can be bent multiple times over on themselves without breaking or warping. At Neptonics, we recommend Spearmaster composite fins, which we sell fitted with custom foot pockets. We have personally been able to bend these fins over on themselves multiple times and they return right to their original form when we let go. Fiberglass fins are, however, susceptible to cracking. If you drop a weight or weight belt on them or accidentally close them in a door, they probably won’t survive.

Fiberglass fins are 20% more efficient than plastics, so traveling 50 meters only takes about 24 kick cycles when wearing fiberglass fins. 

Carbon Fiber - $$$

Carbon fiber fins are the gold standard of efficiency in freediving and spearfishing. While expensive (ranging from $400 to $600 and up), the performance of these fins is unmatched, due to their extreme light weight, hydrodynamics, and efficiency. While you can’t bend a carbon fiber fin over itself multiple times (something you’d never actually even come close to doing on the water), they have a similar operational durability to fiberglass fins. There are options to buy a slightly shorter fin or a slightly longer fin, and it’s important to understand the difference (other than a couple inches) between the two. The shorter fin is designed for reef applications, where a diver needs more mobility to change directions and do small kicks for the agguato technique. The slightly shorter fin length makes it less of a pain to do those kinds of maneuvers underwater. The longer fin is mostly designed for line diving or Bluewater applications, where you don’t really maneuver around much if at all, so the goal is single-direction efficiency.

Another way of understanding fin types is through whether they are reactive or progressive fins. Reactive fins tend to be slightly shorter, and have more immediate traction in the water, which is beneficial if you are trying to keep a fish out of the reef or a wreck. Progressive fins are normally longer, and take longer to efficiently move a diver through the water, but once they do they become significantly more efficient. Progressive carbon fiber fins tend to be preferred for competitive freedivers on a line. Reactive carbon fiber fins tend to be more popular for spearfishing.  

At the end of the day, traveling 50 meters in a carbon fiber fin is more efficient, and will only take you around 15-18 kick cycles if you've gotten the right stiffness for you. All in all, the customizability, hydrodynamics, and efficiency of the carbon material make it the industry standard for serious spearos worldwide.