A critical part of passing selection with a water confidence portion is having the where with all to remain calm while performing tasks underwater.  Underwater training is not just about teaching your mind to stall calm but to train your body  to cope with the rigors of prolonged apnea.

Apnea.  Definition:  suspension of external breathing,

Professional and novice freedivers will regularly utilize apnea tables to condition their bodies for prolonged breath holds.  There are two types of breath hold training tables: C02 and O2 .
-C02 tables condition you to cope with increased levels of carbon dioxide inside your body from the lack of exhaling.
-O2 tables condition you to cope with decreased levels of oxygen inside your body from the lack of inhaling.

Today, we compare the four most popular free mobile apps that provide apnea training:
-Apnea Lite (Android)
-Freedive (Android)
-Freediving Trainer (Android)
-Apnea Trainer (IOS and Android)

#1 Apnea Lite 

This app has a simple setup to select either C02 or O2 tables.  In the menu there is also an option to “play” square breathing; a pattern of breath hold -> exhale -> short breath hold -> breathe, repeat.  There’s the ability to pause, stop, skip or add more time during your table work, which is nice.
The app wants to utilize your best apnea record as a starting point to make your default C02 and O2 tables for you but when these tables aren’t working well, changing the tables can be  a cumbersome process via the settings menu.  The option to create customized tables exist but they currently do not save after you exit the app in the free version.

#2 Freedive 

The freedive app utilizes the basic Co2 and O2 tables based off of your best apnea record, which can be recorded via the app.  The default tables are autogenerated based off of your record and are not adjustable.  But, the app allows you to create your own static and dynamic apnea tables from scratch and save them in the app.  This worked well allowing you to have multiple saved tables to work from and eliminated the need to constantly change a single default table that is seen in other apps.

#3 Freediving Apnea Trainer 

The first thing that set this app apart from the rest was its very creepy icon.  Besides that, the app also contains ads at the bottom and as well as random pops-  enough to provide a noticeable annoyance.  Besides that, the app has your basic O2 and C02 tables that can be modified in the menu area as well as creating and saving custom tables, which is nice.  This app also contains a square breathing exercise, just like the Apnea Lite app.

#4 Apnea Trainer  

This app has a significantly different layout than the other three apps.  Comprised of two circles on the main screen that act as your breathe and hold times, the app can be beautiful, frustrating and confusing all in one.  Edit buttons to change the layout of the circles disappear after a few seconds of starting a table and won’t return unless you start over.  The app comes pre-loaded with a C02 and O2 table that are editable and you may add your own custom tables.  There is no place in the app to time or log a best apnea time.  The app also features a ‘shop’ tab for random freedive gear but also contains a helpful media tab, pointing to a few useful Youtube videos on underwaters, freediving, & breath holds.

Our take:

While no app is perfect, clearly some stood out as performing better than others.  The Freedive app (#2) is the most user friendly app and most recommended by us if you are looking for a free app.  Although it does not have a square breathing option like the Apnea Lite (#1) and Freediving Apnea Trainer (#3) apps, it makes up for it with user friendliness and the ability to save custom tables.
If you are willing to pay a few bucks, the paid version of Apnea Lite; Apnea Master is a great choice.  The Premium version of Freediving Apnea Trainer is equally as good which is available as an in-app purchase on the free version.