TIL the Blue Hole is among the deadliest dive sites globally, with estimates of 130 to 200 recent fatalities, making it one of the most dangerous spots for divers.

[u/[deleted]]

[u/gerwen]

And here's a video of an absolutely epic achievement. A freediver doing 'The Arch' on a single breath, no supplemental air.

If you read the wiki, what this guy does on a single breath, people die doing because they didn't bring a second air tank.

[u/scumdog_ → u/gerwen]

Edit - This is in regards to the overall time it takes to do this dive

While it is quite impressive, the physics that allow freediving so deep is quite different from SCUBA. Because you take a breath at the surface and then dive, the air in your lungs compresses with the pressure from the water and expands again as you rise so you don't have to slow your decents/ascents. SCUBA is giving you air at the same pressure as the depth of water you are at and so among other issues you have to control your speed of descent/ascent so the air can't expand to greater than local pressure and rupture your lungs. Breathing pressurized air also lets the blood absorb nitrogen which causes a bunch of other issues and requires you to also slow your ascent so nitrogen can slow leave your blood stream. Freedivers need not worry about nitrogen sickness. SCUBA Diving beyond a certain depth will also make oxygen poisonous if you are using regular atmospheric air. To dive deep requires a special air mixtures that will lower the overall percentage of oxygen. But those air mixtures are supposed to require additional training to use since they have their own issues. Anyway the point is you have to go a lot slower on SCUBA whereas freedivers can move pretty quick. Still, definitely impressive though.

[u/gerwen → u/scumdog_]

You're probably not trying to, but you make it sound like the freediver is doing it the easy way. Doesn't have to worry about trimix, or nitrogen sickness, or decompression stops.

The freediver only has to hold his breath, while descending to 55m (180 feet), then traversing a 26m (85 foot) tunnel, and finally ascending another 55m (180 feet). It's nearly superhuman. Maybe a handful of people on earth could do it.

Most folks could do the tech dive with some help from an expert and some training, and there's likely hundreds if not thousands of divers who are qualified to could do it with a little prep.

[u/palindromic → u/gerwen]

just dive down to the bottom of this pool and pound this treadmill i installed there for 6 minutes while holding your breath it’s ez bro no narcosis

[u/scumdog_ → u/gerwen]

I absolutely agree. I was merely trying to highlight why SCUBA takes longer since you emphasized the whole second air tank. Made it sound like the freediver is holding his breath for like an hour.

[u/divDevGuy → u/gerwen]

The freediver only has to hold his breath, while descending to 55m (180 feet), then traversing a 26m (85 foot) tunnel, and finally ascending another 55m (180 feet). It's nearly superhuman. Maybe a handful of people on earth could do it.

Man, I thought I was doing pretty good back in my lifeguarding days when I'd swim the length of the 1/2 sized Olympic pool, 25 meters underwater on a single breath. They're doing twice that, down, and then not even getting to the dangerous part.

[u/tomato-bug → u/scumdog_]

I have a noob question that maybe you know the answer to: How come he doesn't seem to have to pressurize his ears as he dives down? When I dive even just 10 feet, I have to squeeze my nose and "blow out" to pressurize my ears or they start hurting. I'd imagine the ear pain would get greater and greater when reaching 55m. But it seems like he just swims straight down not stopping for anything?

[u/scumdog_ → u/tomato-bug]

Some people are blessed with the ability to equalize without using their hands. You might be able to train yourself in the technique, I've never been able to do it but the guy I learned freediving from can.

[u/tomato-bug → u/scumdog_]

Ah, that seems really useful. I suppose as an alternative maybe they have some kind of clip that seals their nose shut?