One of the funnest things in the sport of swimming is developing an awesome underwater dolphin kick. It’s the closest we come to assuming the form of a dolphin or great white in the water. In order to achieve the undulation, leg fitness and flexibility that comes with a great dolphin kick, you need to train it! This means you are adding extra dolphin kicks to your push-offs and starts. This means you are strengthening your legs in the gym. It means you are spending more time on your kickboard doing butterfly kick.

Additionally, there is a piece of swimming gear that you can use to further level up your underwater kick, and that is the Monofin. If you’ve never seen one before, the Monofin is essentially a mermaid fin—a large, two-footed rubberized fin.

Here’s why you should start swimming and training with a Monofin in the pool:

1.      Your kick will get stronger. Swimming and kicking with swim fins is simply a lot of fun. You get to go faster than you generally would. Putting on fins puts your legs to work and will make them stronger and provide you with the strength you need, especially during your races when your legs are getting flushed with lactic acid and you want to push on. Training with a Monofin will make your dolphin kick stronger.

2.      Your ankles will get more flexible. Kicking speed is largely predicated on your ability to get a high range of motion with your ankles. One of the most common mistakes that I see with swimmers trying to improve their kick is that they kick the water down. This is not how propulsion happens—we move forward by kicking water backwards. Once you wrap your head around this indisputable fact, you can begin to address the real issue with improving your dolphin kick—and that is pushing water backwards with the top of your feet. Now, there are lots of things you can do in order to stretch out the ligaments in the foot and the ankle. You can perform ankle rockers when you are outside of the pool. You can do lots of kick, which will help extend your range of motion. And you can also do kicking with a Monofin. The fin will help gently pull your ankle flexibility as your kicking motion will be fuller in both directions.


3.      You will learn how to undulate properly. One of my favorite ways to use the best Monofin is to really work at my undulation. To effectively dolphin kick you should be doing so from your core and hips, and not just from your knees. A common beginner mistake is to kick from your knees, which robs you of a great deal of propulsion and even creates more drag as your profile in the water becomes larger. A powerful way to improve your undulation, and to also balance out your kicking motion, is to do fish kicking with a Monofin. Fish kicking, for those who don’t know, is kicking on your side, either on the surface of the water, or below it. Fish kicking gives you an opportunity to kick in a more natural and balanced manner, and will strengthen the upkick portion of your kick. This will have the side-effect of teaching you how to better kick from your core, achieving a higher degree of undulation in the water.