Vandit Kalia,  12 February 2025

Ask anyone on the forums what the most important gear for divers is, and the answer will typically vary between "mask" and "dive computer", with some people throwing in "regulator".    And understandably so, because each of these has a very obvious and direct impact on comfort and/or safety during the dive.    Fins tend to be forgotten in all of this, especially by most newer divers - people either just use the fins they are given by the dive center, or buy whatever looks cool and/or gets good reviews online, and that's the end of it.  

THE IMPORTANCE OF FINS IN SCUBA DIVING

In 2019, I had a bit of a revelation.   I had been using the same few models of fins since the 1990s, with the Cressi Master Frogs being my favourite fins for pairing with a wetsuit.  Then Cressi, in their wisdom, decided to discontinue them and replace them with some eminently mediocre, generic fins and so I was in the market for a new pair to replace my Master Frogs.    I decided to use this opportunity to try out some of the new fin technology that had hit the market - my last attempt at trying new fin tech had resulted in me buying the Mares Volos back in 2001, a fling that did not last long, but being a gear-head, I was excited to see what new fins the market had.   So I went and bought a few fins to try out, including a model by Tusa with detachable blades (for ease of packing), one by Aqualung which used a system of "gears" to adjust the stiffness and power ratio, and a few other models, proceeded to test these on various dive trips, including to Dumagete and Maldives.

And THAT was an eye-opener!      With one pair of fins, I simply could not achieve neutral trim - my legs kept sinking and since I dive with no weights, there was nothing I could do to fix this.   Trying to take macro photographs with this was an exercise in frustration and my air consumption rate was a good 25-30% higher than normal, as I flailed around like someone on Day 1 of the Open Water course.    With another pair of fins, I was struggling in a current - something that was new to me, as the Master Frogs had never faced a current they couldn't wallop.     For the first time in over 3 decades, I was struggling more than others in a current, and I had some absolutely miserable dives as a result (including missing out on photographing an 8m whale shark because my fins couldn't propel me properly).

So that got me thinking - to what degree are people's dives affected by sub-optimal choices of dive fins?     If you rent gear, when was the last time you paid attention to the fins you were handed by the dive shop?    And let's face it: fins provided by most dive shops - as with the rest of the rental gear - are chosen to be robust, functional and cost-effective, not necessarily the best performance.   And to what degree has this affected your diving?

So I decided to run an experiment - for the next several months, as part of the buoyancy or diving fundamentals class that we conducted, we got divers to try out different fins to see how they got along.   And the results were eye-opening: across a range of experience levels (from recently certified to a few hundred dives), divers found a significant improvement in their buoyancy, trim, ability to handle currents, air consumption and general comfort when they found the right pair of fins.    

That brings up the obvious question - what is the best pair of scuba diving fins?   Or, more specifically, what is the best pair of scuba diving fins for me?

HOW TO EVALUATE FINS FOR SCUBA DIVING

Before we try to answer this question, let's see a framework for the various attributes of scuba diving fins.   Scuba diving fins come in a wide variety of shapes, colours, features, etc, so let's go over how to select a pair that is best for you.

Let's start with 2 obvious attributes that you can use to whittle down your choice of fins:

Buoyancy:   Do the fins float or sink?   And how does that match your legs?     Remember, the fins are the furthest from your center of gravity, so any changes in their buoyancy will have a much greater impact than a corresponding change in your weight belt, for example.     Often times, if your legs are sinking, the solution can lie in your choice of fins.      It is critical that you pick fins whose buoyancy attributes are suitable for your body type - the best-reviewed fin in the world is going to be a disaster for you otherwise.  Case in point - the venerable Scubapro Jetfin, a classic that I absolutely love when diving with a drysuit and which I would never, ever wear with a wetsuit because of how they drag my legs down.

Size:   To the joy of some and chagrin of others, size definitely matters.    As far as propulsion goes, the effects of size are factored in the stiffness and thrust attributes that I will discuss below, but size also matters when it comes to the simple act of packing for dive travel.    Smaller fins let you use a traditional check-in suitcase while larger fins may require a specialized dive bag.   Personally, given the important of fins in overall diving comfort, I would only use size as a tie-breaker when trying to decide between two comparable fins - I would not sacrifice my diving comfort just for a little convenience in travel (in the end, the cost of needing to take a larger bag is insignificant, compared to the overall cost of a diving holiday)

With that out of the way, let's talk about how to evaluate fins when it comes to providing propulsion in the water.   For this, I have created a framework of 3 characteristics:

Stiffness:    This is a measure of how much effort the fins need to be moved up and down.   The  stiffer the fins, the more effort that is required.      Stiffer fins are also better for doing the frog kick

Thrust:    This is how much forward propulsion you get with each kick cycle.   Some fins will move you more, some will move you less.   This is a function of fin design, size and materials used.

Bite:   This a term I have coined for much water-feel you get with the fins.    Swimmers get used to "catching" the water in their palms.   Squash or tennis players will know how some racquets give them a good feel/touch when they hit a ball.    Some fins "bite" the water well and allow for very precise control in the water, making them ideal for small adjustments in the water (eg, when taking photos or manoeuvring inside a shipwreck)    

The basic physics on how propulsion works is quite simple:    the more power you put in, the faster you go.   And in general, more thrust comes from larger, stiffer fins.   The Cressi Master Frogs are a very simple illustration of this principle at work:   they are large blades of very rigid plastic that require you to muscle them around in the water, to which they respond by moving you with alacrity.      No fancy tech or finesse involved - the more muscular effort you put in, the more power you get.

The holy grail of fin technology is to make things easier - to provide more propulsion with less effort.

One way to do so us by using design and technology to reduce the size/stiffness of the blade while maintaining thrust.     This can often be a good trade-off:  for example, a big reduction in stiffness for a minor reduction in thrust can make a fin significantly easier for everyone to use, regardless of fitness level/leg strength.   Channels in fins, varying stiffness at different parts, etc are all techniques used by manufacturers to achieve this, with varying degrees of success.   The trick is to find the balance of stiffness and thrust that suits you.

A more extreme way to achieve higher propulsion is by reducing the stiffness and thrust even more, but requiring divers to compensate by kicking more often.   This is the analog of using high cadence in cycling/high turnover in running:  it reduces the muscular effort involved, but the downside is that it shifts the  stress onto the cardiovascular system, increasing your heart rate and breathing rate.  

Split fins are a classic example of this - they are very easy to kick (low stiffness) and have a relatively low thrust, but that ease of kicking allows you to kick more often, which compensates for that low thrust and provides decent propulsion.    

HOW TO FIND THE BEST SCUBA DIVING FINS

I am firmly in the category that there are no free lunches in science or diving.   In general, to get the most thrust, you need more stiffness and more size (yes, I know... phrasing.  You can stop giggling!).    It can be mitigated to some degree but in the end, there is no avoiding science.

If you are diving in conditions that don't have strong currents, you can get by with less stiff fins that are easier to kick.    But can you always predict the ocean with such certainty?

On the other hand, there is also a practical limit to what kind of currents you will be diving in.  Contrary to some expectations, it is not very common to spend a lot of time fighting super strong currents that put you at the limit - in such conditions, typically the dive leader will either choose to drift or cancel the dive.      And yes, while being able to deal with unexpected conditions is always good, for the vast majority of recreational divers, the choice of fins isn't going to be the deciding factor in how you handle these conditions.

So there is a "real world" range of diving conditions that your fins need to be able to handle, with some variations by location.     

My recommendation is to pick the stiffest fin that you can comfortably kick in your preferred style (flutter kick or frog kick) - it is worth trying a few to see which combination of stiffness/thrust feels best to you.     Everyone will have a sweet spot combination that's best for them.

Then try muscling those fins, as if you are swimming in a current -  make larger/more powerful kicks and see if you comfortably do so for a while without getting tired.    Sometimes a fin that is easy to kick at regular efforts gets much harder to kick when you increase the effort.

After that, see how the fins hold up if you kick faster.     Fins feel great when you are kicking them leisurely but can get very tiring if kicked fast - or sometimes, they may not even keep up with the kicking rate (especially fins with a lot of funky channels and folding zones and such).  

So basically you are trying to get a sense of how the fins behave under your normal kick cycle, under a more powerful kick cycle (one using more leg strength) and under a faster kick cycle.   This combination will give you a good sense of how the fin behaves in the water under different conditions, and which feels better for you.

Photographers and others requiring precision in the water should also try to make small adjustments in the water using just your ankles - feel the "bite" of the fins and whether they give you good feedback and water feel to make precise corrections.

HOW TO PICK A PAIR OF SCUBA DIVING FINS

With a plethora of fin choices out there, it is virtually impossible to try all of them (if at all - most retail shops don't allow you to test fins;  some that do are often limited to only one brand and so biased towards what they sell).     So how do you proceed?

To start with, try out as many fins as you can.   Ask your diving buddies or dive club if they have one.   If not, rent or try out while on a dive trip.     Trying out a few pairs of fins one after the other will also make these differences I have written about more obvious and help you decide what features matter more to you.   Then a good dive center or instructor can help narrow your choices down to a few candidates.

Alternatively, you can also narrow your choices down by asking for advice based on the following:

• Your leg strength
• Preferred kicking style - frog kick or flutter kick
• Preferred buoyancy characteristics of the fins (ie, do your legs go up or down?)

A good dive center or instructor will be able to use these to help you narrow down your list of potential candidates as well.

In the end, some perspective is also worth it - you are not chasing perfection with fins, this long article notwithstanding.   You want a pair of fins that works well for you - and there are many choices that will accomplish that.     So don't let 'paralysis of analysis' freeze you up to much.    

There are always some safe choices that you can get, which have been proven to work well for most divers - your dive center/instructor can advise on those as well.

Safe diving!