Swim Fins 101

A Z2 Swim FinWelcome! If you’re looking for information about swimming fins, you’ve come to the right place. First things first. What are swim fins and how do they differ from dive/snorkel fins? While they seem similar, not all fins are created equal.

Swim Fins are used for swim training (to help you become a better competitive swimmer), and to add resistance to your kick which helps build muscle while swimming. They are most commonly used in a swimming pool. And while you could use them when swimming or training in the ocean, these are not the same thing as “dive fins” or “SCUBA fins” which are used, you guessed it, for SCUBA diving or snorkeling.

There are many differences between the two, but the defining factor is that dive fins feature a longer blade, and are designed for a slow, broad kick, used to overcome the drag imposed by dive equipment. (Divers typically don’t swim using their hands).

Swim fins on the other hand (see picture above) have a much shorter blade, which help to build muscle by adding resistance to your kick as well as many other benefits discussed below.

The Benefits of Swim Fins

We know that swim fins increase the surface area of the foot, providing added propulsion and increased speed while swimming. But how does this actually help you become a better swimmer?

For Strength Training

It may not be obvious at first, but when you’re using fins to swim faster, you’re legs are actually working harder than they normally would (without fins) to maintain that speed. Over time, your leg muscles become stronger which will ultimately allow you to swim faster and longer when you’re not using fins.

But if the goal is to make your legs stronger, why not just swim faster without fins? Well, you could probably kick twice as fast for about one lap, but you’d quickly find yourself out of breath and out of energy.

Female swimmer pushes off the pool wall with fins.

Many swimmers rely on the extra resistace provided by swim fins to achieve a strength and cardio workout.

Why? Because kicking fast puts extra strain on your heart muscle, but doesn’t help your legs get any stronger since you can’t maintain that pace for a long enough time. Additionally, even though your heart rate will be elevated, it will most likely be elevated way beyond the upper limits of your target heart rate, which will quickly result in fatigue. So really fast kicking is no good for a cardio workout either.

Just like with traditional strength training, you should push the limits of your muscles to improve them, but you don’t want to over-work them, or attempt too many repetitions of the same muscle group without taking time off to rest.

By using swim fins, you can work your legs harder without overloading your muscles.

Using Swim Fins for Cardiovascular Exercise

Before we talk about the role swim fins play in a cardio workout, we need to talk about some exercise theory.

First, What is cardio?

The cardiovascular system.

Using swim fins can increase cardiovascular health significantly.

Cardio is a short term for ‘cardiovascular exercise’. The Latin prefix ‘card’ meaning of or having to do with the heart. So in short, cardio is nothing more than strength training for your heart muscle. Swimming with fins is just one of the many ways to get a good cardio workout. You could just as easily run, jog or jump rope. (But swimming is much more fun!) We’ll discuss swimming for cardio in just a moment.

In order to give your heart a good workout, your heart needs to be in it’s target heart-rate range for an extended period of time- usually between 20 and 30 minutes, and you need to be utilizing a large portion of your body’s total muscle mass. For an intense cardio workout, you also need to use both your arms and legs simultaneously.

So why do cardio at all?

The biggest benefit of regular cardio work is a stronger heart. The stronger your heart, the longer you can swim- or perform any other activity for that matter. In other words, the direct benefit of a strong heart is increased endurance. If your heart can supply blood (and thus oxygen) to your muscles more efficiently and for longer periods of time, your entire body will be able to perform better in physical situations which will, in turn, increase strength and stamina.

Target Aquatic Heart Rate

Your heart-rate while swimming or doing water aerobics will be much lower than it is on land, even though you are still receiving the same exercise benefits you would on land. If you’re swimming for cardio, you’ll first need to calculate your water target heart-rate. Remember- it’s NOT the same target heart-rate you’d use for running or jogging. This site indicates that a 13% reduction from your target land heart rate will yield an accurate aquatic target heart rate: http://www.howtobefit.com/swimming-heart-rate.htm

So what does all this have to do with fins?

Here’s the problem. As mentioned earlier, in order to get a proper cardiovascular workout, you need to use a large portion of your body’s total muscle mass when exercising. Over 60% of your body’s total muscle mass is in your legs, so any proper cardio workout must involve heavy use of your legs. When running or jogging, this is easy. You’re already using your legs heavily, so a little bit of arm movement is all you need to maintain your elevated target heart-rate (which is key to a good cardio workout).

When you swim, however, your arms are used heavily for propulsion and the legs are often neglected. Sure, you’re kicking with them, but you’re working your arms far harder than your legs, and this isn’t very good from a cardio standpoint- you want to be using your whole body equally. The thing is, human legs weren’t designed for swimming. They’re extremely inefficient at it. The foot has very little surface area and just isn’t that great at propulsion.

So how can we make our legs work harder and still have enough energy for a solid 20 minute workout? I’m sure you’ve already guessed where I’m going with this: Swim Fins! The title of the site.

Speedo Biofuse Training Fins

Speedo Biofuse Training Fins offer a short, stiff blade for greater muscle-building capability.

Wearing fins does more than make you look funny. They increase the resistance of your kick by adding surface area to your foot. The more resistance, the tougher the workout. And the tougher your legs work the harder your heart works. And it’s this elevated heart rate that, just like exercising any other muscle, makes your heart stronger.

Looking for a change of pace? You can also get a good cardio workout by treading water in fins, and tone your legs nicely while you’re at it!

Cardio for Weight Loss

Weight loss has been directly linked to an elevated heart rate. Although losing weight and burning calories is actually the result of higher levels of oxygen consumption, the heart is responsible for delivering that oxygen throughout your body.

When your muscles demand more oxygen (because you’re swimming, exercising, or running from a man in a hockey mask with a chain saw), your heart rate increases to meet the demand. Since it’s much easier to measure your heart rate than it is to measure your oxygen consumption, we’ll use heart-rate as an indicator of calories burned, even though oxygen usage is technically correct.

As explained above, using fins lets you exercise more muscle mass at a higher level for longer periods of time. And the more muscle mass you work, the more oxygen you use, and the more calories you burn. In short, you burn more calories because you’re able to work harder, with less fatigue.

As a bonus for those trying to slim down, calorie consumption doesn’t end when your workout does- you burn additional calories during the recovery period as well since your metabolism is still elevated for several hours afterwards. You also burn more calories simply by having muscle. Muscles burn calories even when your body is at rest- so once you build them, they’ll continue helping you loose weight for the rest of your life.

For Stroke and Technique Improvement

Many fins are positively buoyant. In other words, they float. That means that when you swim with them, the fins will keep your legs higher in the water encouraging a higher overall body position making you a more proficient swimmer.

Cressi Elastic Short Swim Fin

The Cressi Elastic Short fin is long enough for snorkeling, but short enough to use for training.

We know that the increased surface area of the fin provides extra power to each kick making your legs more efficient at propulsion. But swimming with fins also forces your foot to extend and flex beyond it’s normal range of motion which, over time, will increase the flexibility of your feet and ankles. This increased range of motion will ultimately lead to additional propulsion and a more efficient kick without fins.

For Race Training

Fins allow you to practice swimming at race speeds without fatigue. This is important because at faster speeds, your kick is different, your arms spin faster and your body sits at a higher position in the water than during non-race swims.

Using Your Fins

The faster your kick and/or the broader your kick, the more drag is created. When swimming with fins you want shorter, faster kicks (14-18″ works best) to reduce drag. At slow speeds larger kicks the faster you go, the harder the work.

Choosing the right Fins

Types of Foot Pockets

The foot pocket (the part of the fin where your foot goes) usually comes in two styles: an open heal design, using a strap, and a closed heal that encompass the whole foot, like a shoe would.

The closed-heel design is not adjustable, so they are typically offered in a wide variety of sizes, usually one per shoe size. The closed heel fin design also provides a snugger fit.

The open heel design usually (but not always) has an adjustable strap that can accommodate many different foot sizes. This style of in is offered in a basic small, medium, large, rather than by shoe size.

Aqua Sphere Alpha Fins for Breaststroke

The Alpha Fins by Aqua Sphere feature an open-heel design as well as being an ideal fin practicing for all four competitive strokes.

While an adjustable strap offers convenience in that it is often easier to put on and take off (the straps usually un-clip or unbuckle), a closed heel transfers more power from each kick into the fin, since there is less play between your foot and the fin.

There are a few exceptions such as Alpha Fins which have a strap on design that’s not removable or adjustable. A few brands {which?} also offer a neoprene lined foot pocket which is usually very comfortable and reduces chaffing at the expense of {what is the trade-off?}.

Proper Fit

A good fit will feel snug, but comfortable without being too tight. You don’t want to cut off your circulation, but the tighter the fit, the more power transfers from your kick to the fin. Loose fitting fins are inefficient and will waste your energy.

Closed-heel swim fins typically fit the same as your shoe size, although some brands like the Speedo Biofuse Fins run slightly smaller. If you’re right on the edge between sizes, you should probably go one size larger just to be sure. If the fin slips a little, you can easily add a pair of thin socks to take up the extra space.

Finis makes a good fin sock (called “skin socks”) made of swim suit fabric. Or if you prefer, you can also just use a pair of regular socks. You may also want to try a cheap pair of dress socks, if there’s just a small space you’re trying to fill.

Finis Skin Socks for Swim Fins

These swimsuit-like "Skin Socks" by FINIS prevent chaffing caused by swim fins.

Socks will also help prevent chaffing and blisters while providing comfort- especially with some of the stiffer swim fins.  You will also have some protection from things on the pool deck and the locker room floor.

If you choose to use fins without socks (which I prefer, but you’ll need to experiment and find out what works best for you), you may get blisters when first starting out. A lubricant such as ‘snow-seal’ boot water proofer will help reduce chafing until your feet get used to the fins. Usually after a couple weeks of swimming with fins, your feet will toughen up and the blistering will stop. Just take it slow.

It’s best to try on fins in your local swim shop, or order from an online store with a good exchange/return policy. (I can recommend a few good places to buy online, just drop me a note)

Fin materials

Fins are made from a variety of materials including rubbers, plastics, and foams. Fins can be anywhere from soft and highly flexible to extremely rigid and firm. Firmer fins provide more resistance than more flexible ones. The firmer the fin, the tougher the workout. If you’re just starting our with fins you’ll want to start out with a more flexible blade. The firmer fins should only be used after you work up to them. Think of it like weight lifting- when you first start, you want to challenge yourself, but you don’t want to take on too much at once.

Where to Buy

Some people have emailed me asking for recommendations on where to buy their fins. Your local Swim Shop is a great place to get swim fins if you’re lucky enough to have one in your town. Brick and mortar Swim Shops aren’t very common though, and dive shops don’t usually carry the kind of fins you’ll need for proper swim training. Personally, I like to get all of my Swimming Equipment from AquaGear Swim Shop, one of the best online swim stores in my opinion. They are always extremely helpful on the phone, and I usually get my order in two or three days with their standard shipping. Check out their Swim Fin Section to see the models they have available.

Caring for your Fins

Swim fins aren’t too expensive, but since they’re easy to care for, why not protect your investment?

The easiest way to prolong the life of your fins is to give them a quick rinse with fresh water after swimming. Whether it’s salt from the ocean or chemicals from the swimming pool, these corrosive substances can slowly eat away at your fins over time, which can cause premature failure of the materials and decreased performance. Most pools and beaches will have a fresh water tap or hose you can use. Just ask a Life Guard or facility staff member if you’re not sure. Worst case scenario, you can rinse them in a shower since public facilities almost always provide them.

It’s also important to avoid walking in your swim fins. This includes on the pool deck, or on the pool bottom. The most obvious reason is the rough surface will scratch them. But walking in your fins can also permanently deform their shape. Swim fins were designed for, as the name implies, swimming! They may have subtle curves to their underside that aid in propulsion, but when you walk in them on a flat deck or pool bottom, your weight causes those special curves to flatten. This flattening can not only decrease your fin’s efficiency, but can also add drag to your workout! And that’s a bad thing. (Read the section on how fins work for more details.

To avoid causing damage, you should always carry your fins to the pool side, and put them on while sitting on the edge of the pool, just before starting your swim. Make sure that when you rest between laps (and if you’re using fins you should be resting between laps, see above!), that you’re not standing on the bottom if the lane is shallow.

Side Note: Sometimes fins are used on land as part of a therapy program (for helping people learn to walk again after an injury or accident). Of course this is OK because the fins they use will never be used for swimming.

After swimming, your fins should be stored in a cool, dry location. Be sure to store them our of direct sunlight, as UV rays can cause them to break down prematurely.


Scott T. on August 5, 2011 at 5:23 am.

Hey thanks! I haven’t been swimming in about eight years at least, just been struggling trying to make a living. This summer I got interested in it again, and also bought myself a pair of swim (snorkelling?) fins at my local sporting goods store. I’ve wanted fins since I was a teenager and finally just now at age 32 bought them. I realised that my legs got cramped up almost immediately when I was out kicking hard in the water. Now that I have read your article, I understand just why that happened. I am going to make swimming with fins one of my main activities. Thanks for posting such an informative article! -Scott


Coach Drinkwater on August 18, 2011 at 12:57 pm.

Thanks Scott,

I’m glad you found the article useful. Do you know the model of the fins you have? If you’re trying to do swim training with snorkel/dive fins, you’re going to get burned out really fast since dive fins are meant for slow moving with lots of “torque” (so to speak), by moving people with lots of diving equipment weight on them. Swim fins have a much shorter blade and are designed to move you quickly through the water for a cardio workout, or to train at race speed without as much physical exertion.


Rae Farrell on October 14, 2011 at 11:24 pm.

Thanks so much for this informative article it was just what I was looking for.
I am 55 years old and have been swimming laps (50 laps x 25 meters per) everyday for two months in the pool at our club.
I have lost nearly 50 pounds in that time. (It’ s the swimming and my diet)
I am under ( my choice ) a strict diet ( 2500 calories per day as I am also a type 2 diabetic ) recently diagnosed hence the dramatic life style change.
No meat, dairy, oil, sugar, salt. I know I know but there really is life after cheese burgers.
I am a rule follower a type A personality , a stands for anal I guess but I do get results.
The other day the clubs swim coach watched me swim ( I am very fast) for my last 20 laps then came over and said in her condescending way “”If you want a real work out take off those cheaters”” ( My fins ).
Rather than being rude I kindly replied that they help me to go faster keeping me on top of the water and they provide a much tougher work out for those large muscle groups in my legs.
She basically told me I was an idiot and that she knows better. ( she is older than dirt)
Well, I would never rub her nose in the truth ( boy would I have like to ) but I am so relieved to find that I was absolutely correct and the old bag was wrong.
Yeeees ( My right elbow pumping in a downward motion fist clenched with joy)
Thanks again
aka “Motorboat”


Weston Scheidegger on November 23, 2011 at 10:12 am.

found your webpage on aol and was just what i was looking for, keep it up :-)


George Kapogianis on November 24, 2011 at 6:50 pm.

It’s hard to find knowledgeable people on this topic, but you sound like you know what you’re talking about! Thanks


SARI on December 10, 2011 at 10:19 am.

Which is better for someone like me who wants to tone up & loose fat? Zoomers Fit Fins or Zoomers Gold Swim FIns? THANKS. Sari


Coach Drinkwater on December 23, 2011 at 9:35 am.

@Sari: I recently got samples of all of the Zoomer’s line to try, and I tested them all out in my pool. I’m going to publish a detailed comparison between them soon, but I’m going to say that the Z2′s are probably my favorite (http://www.aquagear.com/finis-z2/). They cost about $3 more than the “Fit” fins and I think they’re better quality materials. The “Fit” catches more water when you swim with them which is good for muscle toning, but what you want to be doing is cardio since an elevated heart rate usually leads to weight loss. (please see my section above on cardio with fins). I hope to publish my review/comparison just after the holidays.


Bob on January 25, 2012 at 9:17 pm.

Just found your web page as I’m (this week) looking to replace my
larger diving fins with some training fins… possibly the Finis Z2 or something
You mentioned you were going to be publishing your review/comparison soon?
Any chance I can see an advance copy?
I’ll be happy to return some edits for you in exchange, if you like.

Keep up your good work



Jacob on January 2, 2012 at 10:31 pm.

Hey, i just wanted to say thanks! ive been searching the internet forever for a good, inexpensive pair of fins( because i’m 13, on the swim team and, well i need a new pair) and while you didnt really help in that aspect of my issues, you did teach me a lot of things. Are you really a coach? and if so, i’d like to know what the difference between the long bladed and short bladed fins are…? you seem to know what youre talking about. thanks!


Coach Drinkwater on January 3, 2012 at 9:00 am.

Hi Jacob,

Thanks for visiting and for your comment!

The long blade fins are usually called “dive fins” or “snorkel fins” because they are meant for use while diving and snorkeling. Divers and snorkelers usually have a lot of equipment strapped on to them, and they need help to move through the water, but they only need to move slowly since they are mostly doing site-seeing.

On the other hand, when you’re training to swim on a team, its a bit different. You want to use short-bladed “swim fins” to 1. increase the strength of your leg muscles and 2. move quickly through the water, at the same speed you would move while racing so you can practice your arm movement without concentrating on your legs.

As for training fins, have you tried the Finis Z2s? Those are the fins I use when I swim for cardio. Have you asked your swim coach if he has any recommendations for you?


Aj Cheetah on January 10, 2012 at 11:41 pm.

Hi Jacob,

I am a runner and want to use swimming to heal my injuries. I have been swimming but my legs sink. I used fins one time in a swimming class and loved them but that was about a year ago. I want to start training mostly by swimming with no running. Just strenght training in weight room and swimming to speed up recovery. I need to buy fins but I do not know which ones to buy. There are a lot of different kinds out there. Long ones, short ones..fins with splits through them. I am confused. I am not competitive in swimming though i am training for triathlon as well so soon I will be. For now though, i just want to get my basic swim techniques down…however long that will take, i dont mind. I just want my cardio in the water to increase and leg strength etc. Can you help me decide which fins to buy first, then which to buy after I have outgrowned the first buy etc. I would really appreciate it. Any other swimming advice would be great too! I just want to to a great swimmer so I can combine that with my cheetah speed on track/running get a bike and become a well balanced athlete!



Aj Cheetah on January 10, 2012 at 11:42 pm.

oops! this was directed to the CoachDrinkwater of website and not Jacob.


Val on January 30, 2012 at 4:04 pm.

Coach Drinkwater…I’ve been exploring the internet for days looking for a good pair of swimming fins for my 4.5 year old son. He’s been swimming for over a year now and his instructor recommended swimming fins to help with his positioning and strength in his legs. I’ve look at the web site you recommended in this article but they only have the open heel ones. Can you recommend a brand that would work best with his age? He is a very good swimmer, which might be hard to believe considering his age. Thank you.


Jesus Nieves on February 9, 2012 at 9:03 am.

Very informative article. Thank you very much.

Added to my favorites.


Cookie on February 14, 2012 at 12:47 pm.

I am a runner by nature for over 10 years.. and began training for a triathlon… The bike was a fairly easy transition, but when I got in the pool, i was seriously out of breath (without fins). From reading you article, I should get some swim fins, and probably slow down to keep my heart around the right target zone.. any other recommendations for a runner trying to be a swimmer?


Dagmar on March 27, 2012 at 8:19 pm.

Can you tell me the difference between split and uncut fins? I assumed that the split fins put less stress on your knees and hips because it sorta guided the fin straight up and down, as opposed to an uncut fin which would kind vacillate back and forth (wiggle) as it went up and down and put stress on your knees.


Meghann Douglas on April 3, 2012 at 3:03 pm.

HELP!!!! I have blisters on pretty much every single toe from ill-fitting fins (discovered the hard way that you cannot make up that space with socks, even neoprene ones). My purpose is weight loss, 52 pounds to date yay me, and swim 1500m every noon hour on work days. My first fins had soft silicone feet which ripped. Next I tried blue zoomers that were slightly big and my feet are a mess. Bandaids do not stay on long enough (40+ minutes), white athlete tape goes paste mucky so it won’t even hold bandaids in place, “liquid skin” just makes the skin sticky (proof?? I broke open two old blisters today).
I now have excellent/tight fitting Tyr Burners which I love, blade size is just right to take the work off my arms. But my toes are bad…. blisters healing on 8 of them.
I don’t think there’s room for socks in the foot of these fins …. would ladies nylons work???? Any other suggestions other than giving the fins a long rest (and getting sore shoulders swimming that much at my weight)??


Jeanie on April 17, 2012 at 2:01 am.

What would you recommend for a beginner swimmer starting off on pool routines?


Herb on April 17, 2012 at 11:10 pm.

Very informative.
I am a 74 yr old fly fisherman and just bought a dry suit to wear instead of chest waders for the sake of safety in the surf or when fishing on a tidal flat where the rising water level may cut me off from the way back to shore. I was considering getting a pair of short fins to provide more efficient use of my legs while swimming. My hand will be occupied holding my gear so will be useless for swimming.
I am afraid that long fins will be too stressful.

These fins would have to be used over my dry suit booties.

Your opinion would be appreciated,


Jermaine Br. on April 18, 2012 at 3:43 pm.

Hi Coach, I have been in the water since as early as I can remember. I Am 22 now and I am now a waterfront director at a summer camp. We have a beautiful lake and from time to time a like to do sprints across the lake. Sometimes I use the fins that we use during our Lost Bather Drills. These fins use an open heel strap, which work fine to dive to the bottom of the lake. However when I use them to swim across they seem to slip off when I go really fast. I have also tried the fins that encase the foot and have the same problem. I am around 6’9 and wear a size 15. I was wondering if there were fins that were designed to come up to the ankle so that water does not push the fins off the foot. I know my feet are pretty big and I might have to find a custom fit. However bigger is not always better. I like the smaller fit due to the control, but of course they hurt, and if i wear them too loose they slip off after a few kicks. Any ideas?


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