As a freediver, the author is not correct that “freedivers often hyperventilate.” Not hyperventilating before diving is one of the most important safety rules i

As a freediver, the author is not correct that “freedivers often hyperventilate.” Not hyperventilating before diving is one of the most important safety rules in freediving. It drops your blood CO2 so you don’t feel like you need to breathe, but doesn’t actually increase your O2- leading to losing track of how long you’ve been down, and blacking out. Instead, you just learn to handle the feeling of high CO2, but use that feeling as a timer to tell you when you’ve been down too long.