How Long Can You Live Underwater?

In 2023, Joseph Dituri set a world record for the longest continuous stay underwater. And that 100 day stay had effects on both his body and mind. Scientists have been studying the effects of living underwater since the 1960s, but how close are they to answering just how long we could stay down there?

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[siberx]

This video didn't really highlight/clarify it, but the notable thing about these stays is that they were done _at pressure, _ where the breathing gas in the habitat is the same as the surrounding water. This makes it quite different from submariners, who are in an atmosphere very similar to that on the surface and are just dealing with the cramped space and isolation considerations but not the physiological changes associated with breathing gas under pressure for long periods.

Helium, as weird as it sounds, is frequently used in gas mixes breathed at depth specifically because it has very low "narcotic potential". Commercial saturation divers get used to this and can converse regularly with each other despite the strange sound, and their operators/handlers can usually learn to understand them as well but communicating with other people is usually done with a pitch shifter to restore a more normal tone to the voice.

In addition to helium, hydrogen is sometimes mixed in for a similar purpose although this has additional risks/concerns due to its flammability, especially because oxygen is obviously also present in the breathing gas.

In terms of oxygen, while breathing regular air at depth means you're exposed to higher levels of oxygen which is potentially damaging long-term, it's also possible to provide a breathe a "hypoxic" gas mix that contains _less_ than the usual 21% oxygen. While this is unsafe to breathe at the surface, as long as the _partial pressure_ of oxygen meets or exceeds 0.21 atmospheres, it's just as effective at oxygenating your blood as normal air would be at the surface, so your tissues still get all the oxygen they need without being exposed to higher dangerous levels. Normally these mixes are only used at depths where the normal percentage of oxygen becomes acutely toxic (about 1.4-1.6 atmospheres of oxygen partial pressure, which occurs at 70-80m) but there's no reason you couldn't use the same trick to alleviate the risks of chronic high oxygen exposure at lower depths and partial pressures too.

The humidity consideration is interesting. If you wanted to have "moon pool" style easy access in an underwater facility, it would make sense to close that space off from the rest of the base with some kind of a door and dehumidify the rest of the working/living space to keep it at a more normal indoor humidity to prevent infections and issues.

[josephgermany]

I volunteer for a year minimum. If they're providing me food, entertainment, and a "to-do" list of tasks while I'm down there, I'd be completely content. No different than what I do now except I'm not currently surrounded by water.

[RyRy]

you know, it honestly feels like mammals are just real good at adapting to the water. the fact that we know we can survive underwater for extended periods of time is kinda amazing!

[caspenbee]

The most interesting thing from Dituri's work for me (from a radio interview I heard), was that he was naturally sleeping like 4-6 hours a night but in REM for the majority of it. He said he felt great because of it. I think about that when I can't sleep at night or wake up still tired!

[FNLNFNLN]

Let's be real though, the record for living underwater is probably some nuclear submarine crew that isn't allowed to talk about it.

There are SSBNs patrols that are known to be longer than 100 days - much longer. The odds that there's a stretch of time during those patrols where the sub is completely submerged for longer than 100 days is pretty damn high.

[obikNobi]

I’ve been playing subnautica for the past 3 weeks and this video is perfectly timed

[DoubsGaming]

I love this, it's cool to see humans pushing the limits of what's possible.

[FrozEnbyWolf]

"I rejected those answers; instead, I chose something different. I chose the impossible. I chose... Rapture."

[troyclayton]

Great video. I have to admit, I thought you meant actually living in the water. That would be something. This seems more like living under pressure, and the water just happens to be there. Does depth matter for this record, or can the top of the structure be just a foot or so down? edit: Why doesn't the 111 day, longest submarine dive, hold this record?

[ShadowDrakken]

It's so weird to me that people talk about how hard it is mentally to live alone for periods measured in days. Like seriously? Give me years, I'll be happy the entire time.

[CaptainMarvelsSon]

Give a Twitch streamer the best gaming equipment, and they could live down there for years without a care in the world about where they are.

[blazebluebass]

Man just needed some time alone to chill and came up with this idea :D

[BenB]

@1:50 She says they want to breath less because it is more exhausting to breathe dense air. But the more obvious cause is because there is three times more oxygen per breath, so they just don't need to breath as much, also explains the lower heartrate and BP, their oxygen saturation was probably consistently really high.

[little-wytch]

I learned, rather painfully, while I was at space camp as a teen, that I cannot scuba dive. The pressure at just 10m down triggered the worst migraine I've ever had and I've dealt with them all my life, so that's saying something. Otherwise, I would love to try living under the sea like that. I'm already a fan/proponent of the tiny living movement, so the small space wouldn't be a problem for me at all as long as I had communication access. Perhaps if such a living container could be fitted with a decent and clear window, or perhaps a periscope, and anyone down there had at least 2 hours a day of access to stare out into the distance, perhaps in 30-minute intervals, that might mitigate the temporary vision issues? Or maybe VR?

[kitefan]

The success of an all female crew of scientists and one engineer: Ann Hartline, Sylvia Earle, Renate True, Alina Szmant, and Peggy Lucas Bond spending 14 days in Tektite II gave NASA data to help it decide women fared as well (and sometimes better) in difficult conditions. This contributed to the choosing of female astronauts in the US.

[hsavietto]

Well, Sebastian already told us that it's better down where it's wetter.

[TroyBrinson]

This is one of the few times I was woefully underwhelmed by a SciShow episode. Maybe establishing the difference between an “Aquanaut” and a “Submariner” as a baseline might have made it seem more interesting, but Boomers go out to sea and stay under for Six months straight. Tens of thousands of Sailors have done that.

[capnstewy]

Are you sure 100 days is a record. Some of the surveillance subs like the Nautilus stay submerged for very lengthy tours.

[missoulaty]

He missed his daughter's graduation for this. Now whether or not that was not okay to do it depends on every family situation and individual relationships.
But that being said I would love to see a video on the personal cost of scientific breakthroughs that pioneers have had to go through in the past?

[shaider]

As a fan of Sealab 2020 and SeaQuest DSV, this seems to be a good idea if done properly