Freediving Fins Explained

By David Fialkoff •  Updated: 01/07/21 •  8 min read

The first thing that you will notice on freedivers are their uniquely-shaped, long diving fins. These called freediving fins that are long and elegant. They are used to propel divers underwater to get to depth and chase fish when spearfishing.

Compared to your feet, wearing freediving fins displaces more water and offers more propelling power. Choosing the best diving fin can be overwhelming. This informative article will guide you on finding the right fit and sizing, using long fins, and determining if it is suitable for scuba diving.

Why Do Freedivers Use Long Fins?

Compared to those who do snorkeling and swimming, freedivers often wear long fins. Walking while wearing these fins might be complicated and ridiculous, but it is a piece of helpful equipment when diving deep underwater. Freedivers use long fins so that it displaces more water per kick. It can let them propel faster and more efficiently. With longer fins, you use less energy and effort per kick.

This tweak is considered highly efficient as you can cover more distances with fewer kicks. You spend less energy and oxygen while adventuring the depths underwater. Long freediving fins basically offer less input for more output. Oxygen is saved and utilized efficiently for your brain and body so you can dive longer and deeper every time.

How Do You Fit Freediving Fins?

Excellent fin performance will greatly depend on the fitting for your feet. Freediving fin should feel like an extension of your feet, and It must feel natural and comfortable so that you do not feel any pain when diving. A natural feel can let you easily adapt to how to use the fins. Having a loose pocket on your heel is not a good fit as it can waste energy with every kick.

Every manufacturer offers different fin sizes. You should always check their sizing chart carefully and don’t hesitate to ask any inquiries to the manufacturer. For you to get a comfortable diving fit, it is advised to wear neoprene socks inside the fins. The socks will give you a good fit and will also keep your feet warm. Manufacturers also expect you that you wear socks while wearing the fins. Usually, they expect you to have neoprene socks that are 1.5 to 5 mm thick. The sizing charts are a big help when adjusting the size of the fins when you want to wear it barefoot. If you plan to wear it without socks, be sure to choose soft rubber on the contact points on your foot to make it comfortable.

Manufacturers also offer insoles that are placed inside the foot pocket to make fin sizes smaller for a suitable fit. These insoles allow you to wear thinner socks if ever the thickness is uncomfortable for you. An excellent fit is vital to the performance and comfort for your freediving fins. If it is too large for your size, you’ll waste energy whenever you are kicking. A small size will be uncomfortable as it will cramp and pinch your feet every time you use it.

Can You Scuba Dive With Freediving Fins?

Yes, freediving fins can be used for scuba diving. Divers usually prefer these type of fins rather than traditional scuba fins due to their efficiency. Scuba diving with these fins can let divers displace more water, propelling them quicker underwater. One of the downsides of these diving fins is that it requires practice to and a certain amount of skill to use it. You cannot use these when exploring tight spaces or going close to reefs.

Are Long Fins Better Than Short Fins?

Long fins give you more distance and thrust. The main downside, when compared to short fins, is that it requires more energy and muscle power to be effective. Short fins give less thrust but require less energy and muscle power to be effective. If you want more power with every kick, you can choose long fins. These are great if you have strong leg muscles and also if you are adept in diving underwater for a long time.

The length of a fin can be compared to bicycle gears. Short fins are like low to medium gears while long fins can be compared to high gears in a bicycle. With a long fin, you can unlock your full potential when diving as these require you to effectively use your leg muscles. If you have strong legs, you can feel that the thrust is much more powerful than short fins. Long fins are also excellent for emergencies because you can get to the surface quickly. You can rush up to the top from the depths by utilizing the long length of the fins.

Long and Short Fins In-Depth Comparison

Long Fins


Long blade looks like your common snorkeling fin. These fins are made with a more flexible heel, longer length, and a flat edge designed to create more water resistance and a powerful wide kick. Because these fins have a longer blade, it tends to be more flexible. A disadvantage of it being flexible is that it decreases its longevity due to the material fin’s material being twisted and bent for many times.


With every kick, you create more resistance and flexibility, and you can cover more distance and surface area. The fin can also help build stronger muscles used in diving. A longer fin can propel you much quicker than a shorter fin.


Because you have a longer fin, the range of motion for your feet is limited. It is much more challenging to replicate your short, natural, and quick kicking style. Because of the fin’s larger size,

Short Fins


Short fins are significantly smaller and shorter than long fins. These fins commonly extend a few inches from your toes. Because they are short, they can come in different styles and shapes. You can have angled or flat edges depending on your needs, and the fins can target different muscle groups and strokes. Since short fins are short, they are less flexible and a little stiffer when using it. Short fins have a longer lifespan because they do not flex much and do not stretch out compared to long fins. Because these fins have a shorter length of the blade, the legs can mimic a natural swimming kick.


You can make a quick tempo using short fins for your underwater adventures. Short fins provide you with a higher kick rate with optimal propulsion when diving underwater. It is great for beginners, as it is ideal for correcting mistakes when diving. Short fins also mimic natural race speed and build stroke-specific leg muscles.


A higher kick rate means that you will burn energy faster and also tire your muscles quicker. It requires more effort to be in the speed that you like when diving.

What Size Freediving Fins Do I Need?

Sizing for your freediving fins is like finding the correct shoe size for your feet. The sizes of these diving fins, when compared to regular shoes, are quite minimal.

A typical rule when it comes to diving fin sizes is that men should choose fin sizes that are the same with their shoe size. Women, on the other hand, should choose a size smaller than their shoe size. If you want to wear open heel fins and you are going to wear boots, buy the boots first before trying out the fins. You should have your diving boots on when trying out the fins to get the correct fit.

Try wearing the open heel fins with boots so that you know how they feel and how comfortable they are. Wearing boots with your fins sometimes demand a size larger depending on the sole and thickness of the boot. The diving fins should fit comfortably like your shoes. They should feel not too tight or loose, just the ideal fitment. It should feel snug without feeling cramped.

When wearing open heel fins, you must adjust the strap to the loosest position and then insert your foot. Adjust the strap to fit snug and secure. Your foot should extend past the back of your boot heal with a few inches. The upper lip should line up with the instep. The foot should not go too far forward in the pocket, if it does it means that the fin is too large.

If you choose a full foot dive fin, then the fit should feel snug and secure without too much space. It also doesn’t have to be too loose that it wiggles. The fin should not be difficult to put on.

For these two types of fins, you can do the shake test to see if its proper fit. You can sit down and shake your foot while wearing the fin. Shake it in all directions, and it should not feel cramped. There should also be no pinching or rubbing while you’re shaking it. It must feel secure and comfortable. If you feel that it is so tight and you think that your feet are constricted, try the next size up. If it wiggles around too much while shaking it, go one size smaller.

David Fialkoff

David Fialkoff is the founder of Spearfishing.Live, a site that's dedicated to the sport of spearfishing. He is a full-time digital marketer and loves to spend time chasing fish underwater on the weekends.