I recently bought some fins... Short, much stiffer than some fins used by divers these are more aimed at surfing.

I can feel they make me faster but am struggling with technique. I feel I'm fighting them and it's very tough on my ankles.

Can anyone offer any advice on how to use them properly?

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  • All divers use fins :) but they have different lengths - if you call them 'flippers' at my dive club you'd end up with a Beer Fine! so I popped in an edit. Can you add a photo? They sound like vented fins - which are shorter than some fins, you tend to exert yourself less with these.
    – Aravona
    Sep 8, 2016 at 9:23
  • Your ankles are getting tired because you're suddenly putting significantly more stress on them. You need to ease into it and give your ankles a chance to strengthen.
    – ShemSeger
    Sep 8, 2016 at 17:38
  • @ShemSeger but my concern is the stress is from improper technique not simply "it's like my feet are a lot bigger so the forces are greater". I think I'm trying to swim normally with them, and probably my swimming technique is either bad, or should be adapted.
    – Mr. Boy
    Sep 9, 2016 at 11:04
  • Keep your fins in the water, not the air. Point toes. Swivel at hips.
    – WW.
    Sep 13, 2016 at 12:10

4 Answers 4


I am a 25+ year scuba divemaster. Alas, poor fin kicking technique is very common, even among experienced scuba divers.

First of all, selection of a fin which is too flexible is better than one which is too stiff (within limits). If you sometimes use a full 7 mm (1/4 inch) wet suit and other times no wet suit, you likely need two sets of fins. Same for snorkeling/swimming versus scuba. The extra bulk of wetsuit/tanks/weights/BCD is appropriately matched with longer and stiffer fins than when skinny dipping. (I am not sure if it is proper when wearing only fins to call it skinny.)

It is nearly impossible to select the appropriate length and stiffness in a store (at least by a novice). Fins need to be test driven. One lap in a swimming pool is usually enough to determine a good match.

Fins are designed with a variety of parameters. One of the most important is their buoyancy. If thrown into the water, do they sink or float? Sinking is good for kicking technique—especially on the surface (swimming) where density helps keep the fins in the water. If you'll be at depth (scuba), non-buoyant fins are more comfortable and easier to control—unless your swim will have elements of Cirque du Soleil. However, when removing the fins, there is a definite advantage to buoyancy so that $150 fins do not immediately tumble 700+ feet to the bottom between the Galapagos Islands (darn!).

The most common fin technique inefficiency is "bicycling". The knees should not be significantly bending. This causes the fin angle to move a lot without moving through much of the water, so it provides little propulsion but a lot of wear and tear on the feet, ankles, and knees.

Efficient kicking motion comes from the hips with the knees kept stiff. If done correctly, it won't be possible to rapidly kick—and that's okay. This video shows great kicking technique. Though he "dolphins" as for a monofin, but it works well with two fins, too. Notice how he moves the fins through a great distance but hardly flexes the knees.

This video clip shows both frog kick and flutter kick (the latter I derogatorily call bicycling). Frog kick provides nice kicking variety because it uses an entirely different set of muscles. The flutter kick does have its use: the video demonstrates how it can be used to prevent kicking up clouds of silt and minimize coral reef damage when swimming near the bottom.

By using long, patient kick cycles and keeping the ankles relaxed, stress on the ankles should be minimal. If you do feel the ankles getting sore or tired, stop, relax, and then continue with gentle large motions instead of rapid tiny kicks.

  • This is great information for diving but I do think the asker may want to inquire about surface swimming - not sure though
    – Avik Mohan
    Sep 8, 2016 at 16:46
  • 1
    @AvikMohan: The last paragraph is particularly relevant for surface swimming (as well as all others).
    – wallyk
    Sep 8, 2016 at 17:34
  • The flutter kick can be the difference between life and death when cave diving. Kick up silt in a cave and your visibility suddenly goes to zero, which can easily disorient you.
    – ShemSeger
    Sep 8, 2016 at 17:40
  • @ShemSeger: Yep. In my wreck diving instruction, we emphasize kicking as little as possible. Instead, pulling on lines or pushing off bulkheads and whatnot to move around.
    – wallyk
    Sep 8, 2016 at 18:10
  • 1
    Also - that first video is great. That "whole body undulation" looks just like watching the swimmers in the Olympics and is something I've never figured out how to do!
    – Mr. Boy
    Sep 9, 2016 at 11:14

Firstly, I must ask, is this for surface swimming (e..g snorkling) or for diving? I myself get so fed up with trying to use fins for surface swimming that I simply refuse to anymore, and I think for that case it's a personal thing. For me it just doesn't propel me much there, and constantly is an issue with breaking the surface and not getting much out of them, and they put heavy strain on my ankles. If I do have to use them, I'll swim sideways so that the fins don't ever break the surface of the water much. This works very well but is slightly annoying. This method seems to correlate with this video which shows swimming with and without fins for the stroke-of-choice for the Navy Seals (allegedly).

For diving, if I'm really trying to move using them I'll keep my feet locked in a 'toes-pointed' orientation and knees a little bent, but really make a full, smooth motion from the hips (allowing the knees to bend and using my quadriceps when needed) to move forward.

  • For swimming, maybe also for body boarding... Those guys always use short stiff fins. I'm not after performance, just a bit more oomph as a weak swimmer... And to allow me to snorkel using lazy legs and no arms
    – Mr. Boy
    Sep 8, 2016 at 16:51

Just to clarify, short, stiff fins are often preferred by body-surfers (and I believe body-boarders, although I don't body-board) for several reasons:

  1. The swimmer usually has only a handful of kicks to accelerate and take off on the shoulder of the wave. Softer fins have a slight 'lag' in the acceleration phase, and put less pressure on the legs, but at the cost of less peak power. For the few kicks while 'taking off' on the face, the swimmer puts in every bit of power they have.
  2. Once on the wave the fins are used (in combination with the leading arm and body) to direct along and up and down the wave, often kicking at the same time. A soft fin is deformed (including torsional forced) by the strong forces of the wave, giving less directional stability.
  3. As a more minor point, many body-surfers want fins which float in case they get ripped off. Rubber floats and is more rigid, silicone sinks and is more pliable. The shape of the fin however also contributes to pliability.

Overall, if you have a weak kick and weak ankles, start with soft fins of medium length. If wishing to body surf big waves rather than ocean swim, you will eventually wish to move to short stiff fins, but build up with mid length soft fins first.


It seems like you buy bodysurf/bodyboard fins as @Brent point it out. Lifeguard (like me) enjoy it too, as it allow you to do medium length sprint (50 to 100 meters, like 100 to 300 feet) at record speed, while being easy to carry in your hand all day long.

These are great for strong acceleration, sharp turn, quick dive under waves and take waves to surf it. However, even for a skilled swimmer, it's not ideal for long swim, as it will put severe pressure on your ankles/knees, as they are really not flexible.

To deal with the technique itself, you may use freestyle stroke for surface swimming. If you want to do long swim, rely on your arm to rest your legs, while making long and slow yet poweful kick with your fins, keeping your legs straight (don't use your knees, you will lose power). For underwater swimming, I think you may look at @wallyk answer's.

As a side note, always test your material in a swimming pool, or worst case, in controlled sea/lake environnement with lifeguard, green flag lift.

  • 1
    Just a note not all swimming pools allow fins to be used (UK) so this point whilst best practise may not be practical.
    – Aravona
    Jul 31, 2019 at 8:23
  • @Aravona Sadly, same problem for me, other side of the Channel. However I tend to think that I you live near the sea, fins are more accepted in pools. When I go to the pools near my home (ocean at 15 km), in most of the case there is a fin reserved swimming line. But when I go in other, more inland pools, while I'm on a trip, it is simply banned...
    – Cailloumax
    Jul 31, 2019 at 8:30

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