What Happens to Your Body During a Freedive?

ניר כהן
Jul 25
2 min read

Freediving isn’t just about holding your breath it’s about unlocking powerful, natural responses that lie deep within the human body. Whether you're diving to 5 meters or 30, your body is doing amazing things to protect you, adapt, and go deeper.

Let’s dive into what actually happens inside you when you hold your breath underwater.

1. The Mammalian Dive Reflex

This is your built in survival system. When your face touches cold water and you hold your breath, the mammalian dive reflex kicks in just like it does in whales and dolphins.

Here’s what it does:

Slows your heart rate (bradycardia)
Constricts blood vessels to keep blood in the brain and heart
Preserves oxygen by reducing muscle activity

This reflex is strongest when you're relaxed—and you can train it!

2. The CO₂ Buildup & Mental Game

As you hold your breath, carbon dioxide (CO₂) builds up in your body not lack of oxygen. That “urge to breathe” you feel? It’s caused by CO₂ rising, not because you're out of air.

Learning to understand and stay calm during this stage is a key skill in freediving. We teach breathing techniques and mental strategies to manage this response with confidence and awareness.