Eli5, how is it that Scuba divers typically have to squeeze their nose and blow to equalize the pressure in their ears every few feet, but those who free dive can sink 20-30 feet in 10 seconds, and be fine while not visually equalizing?

Question

Is the ability to breathe what changes this, or is there some other technique behind it?

In: 55

Answer 1

For starters not all people have to use this maneuver to equalise pressure. Some have control of the muscles in their jaw/ears to do it at will without having to induce movement by blowing through their closed nose. Can it be learned? I don’t know, maybe. I’ve been able to do it since I was a kid and nobody ever told me how it’s just always been something I did.

Also not equalising needs a large depth difference to have bad consequences. For depth differences of a few meters at worst it just causes discomfort, so a free diver just jumps into the water, sinks a bit, may feel some minor discomfort, but he just swims back up just like that. Divers on the other hand will spend a lot of time in the water and will go to greater depths, so they do it constantly for three reasons

1) To not feel discomfort or pain all the time they’re in the water

2) To avoid damage to their ears as they go to greater depths

3) It has to be done progressively every few meters because if you go deep down and then do it the sudden change in pressure can cause significant damage.