When is the right time to learn mouthfill?


While talking with experienced divers or through interviews, I often notice a certain “reluctance” to teach mouthfill. We often hear sentences like “you don’t need the mouthfill to go to XXm”, or “it’s too early to learn the mouthfill”. Some instructors even refuse to teach it in detail during an AIDA4, considering that it is more “penalizing” than anything else… If I can somehow “understand” this kind of reflections, I find that they are often awkwardly stated with an almost laughable effect reminding us of those “grandmasters” full of mystery who, facing the hero at the beginning of the movie, would say “he is not ready” without any further explanation.
I will therefore try to discuss with you logically how to identify the right moment to learn this equalization technique and why learning it too early is likely to penalize you more than anything else. I will also start from the assumption (which is of course not mandatory) that you want to progress in your freediving practice.

What is mouthfill ?

The mouthfill is an equalization strategy. It consists of transferring a large quantity of air into your mouth at the beginning of the dive (usually between 10m and 30m) and using this air (and only this air) to equalize for the rest of the dive. This is a powerful strategy whose main advantage is to eliminate any air transfer between the lungs and the mouth after exceeding the depth corresponding to our residual volume.

Is mouthfill difficult to learn ?

Learning and mastering the mouthfill is complex, it requires the control of muscles that we are normally not consciously using, it also requires total control of what is happening in our mouth as the volume of air available is reduced, we must adapt the movements of the tongue and cheeks to continue to be able to pressurize this air while keeping the soft palate in a neutral position. I am aware that stated like that, it can seem complicated. And let’s be clear, it will probably be complicated at first. But it is not “very complicated”. In fact, if you start by practicing a few exercises, if you put all your attention during your dives the technique itself will come pretty quickly. Of course, it will always be perfectible and a total mastery will take years of practice, but learning an efficient base is not at all difficult.

Why do so many freedivers encounter problems in learning mouthfill ?

As I explained above, learning the mouthfill requires that you be able to give it your full attention during your dives. For this, your dives without mouthfill must already be complete and perfect. Duck dive, line orientation, body position, finning technique, freefall timing, freefall position, relaxation during freefall, turn… All these basic elements that make up a dive must not only be mastered but must also be done on “autopilot”, with an empty mind and without requiring any focus on your part. If you are not 100% on autopilot during your dives, you will simply not be able to concentrate fully on your mouthfill, and from “difficult to acquire”, this new technique will become “very difficult to acquire”. You then risk encountering serious blockages and lose a lot of time in your progression. Yes, there is an “order” in which to learn and this order is not just there to annoy you, it is mainly there to facilitate your progress. The mouthfill is one of those things that you should learn last and learning it too early is the number one source of difficulties generally encountered in the acquisition of the technique.

What will happen if I try to learn mouthfill too early ?

In the beginning, in addition to being complex, the mouthfill can be particularly uncomfortable. It will take time and many dives to make it really enjoyable. If you learn it too early, your lack of relaxation (potentially linked to a too perfectible technique) will add exponentially to this new sensation and your dives may become a negative experience in terms of pleasure. This negative experience will create tension and frustration which will penalize you even more for your future dives and you risk entering a potentially endless vicious circle. Learning the mouthfill too early can be like trying to learn to jump when you can hardly walk: you might not find it very funny and it might “traumatize” you more than anything else. For my part, I clearly learned the mouthfill too early in my career, I was not yet on “automatic pilot” in my dives, and learning the mouthfill turned out to be a particularly unpleasant experience that took me a long time to make acceptable and then enjoyable. During all this time, I was never really able to increase my results in a satisfactory way and it is only a change of attitude and philosophy towards apnea in general and equalization in particular that allowed me to “unblock” myself regarding this technique.

So, how deep do you have to be in Frenzel before learning mouthfill?

This is generally the way things are presented and personally, I’m not a fan of it… To partially answer this bad question, at the risk of shocking some people, my answer would be 30m. Why 30m? Because if you are neutrally buoyant at 10m, it means that you already have about 10 seconds of freefall and that you are already doing “full” dives. But as I explained, I think this is the wrong question… Indeed, more than a depth, it is your attitude and the quality of your dives in terms of relaxation that counts. In fact, if you are “stuck” at 30m and want to learn the mouthfill to be able to go deeper, then you are absolutely not ready and you should try to increase the quality of your dives and your relaxation (by being relaxed, the frenzel will easily take you to 40m). On the other hand, if you are diving in a perfectly relaxed way at 30m and want to learn the mouthfill by curiosity and extend your knowledge to favor your long term progression, then you will have no problem and it is absolutely not too early to start practicing this new technique. In the same idea, even if you are able to dive to say 45m in frenzel but that these dives are always in “challenge mode” and that you do not take full advantage of your freefall, you are still not ready to learn mouthfill in good conditions and improving the quality of your sensations must become your priority, mouthfill will come next.

Why learning mouthfill then ?

It is perfectly possible to dive to more than 70m without mouthfill and wanting to learn mouthfill only to increase your depth is not necessarily the best entry point to have. However, the mouthfill remains an indispensable equalization technique to master for any serious freediver. Indeed, it is the technique that (with equal relaxation and general technique) limits the risk of injury the most. Moreover, if its practice may seem unpleasant and unnatural at first, I assure you that with practice, eliminating the transfer of air between your lungs and your mouth will make your dives so much more pleasant and you will naturally be able to increase your depth in complete relaxation. And yes, in the end, a controlled and pleasant mouthfill equalization along with good training will allow you to dive deeper.


Relying on a depth to decide whether or not to learn mouthfill doesn’t really make sense, what matters most is that you are able to dedicate 100% of your attention to it. 30m seems to me to be a minimum because if you dive shallower, it means that you still have other skills to acquire in priority. Not following this order of acquisition of skills and learning mouthfill too early will clutter your mind during your dives and the whole of your diving will be penalized. If you have too many things to think about, you won’t be able to do any of them properly. On the other hand, if you learn the mouthfill at the right time and in the right conditions, you will limit the risks of stagnation and will keep the pleasure in the practice of your favorite sport.