Seems like you can float on your back forever, without really getting tired. When people drown in lakes or oceans, why can’t they just float until someone rescues them? I get it if you’re wearing clothes heavy with water, but if you were already swimming, or at least dressed for it…?
In: 851
A few reasons.
* Drowning typically happens to people with little experience swimming, like children, or when more experienced swimmers become cold or exhausted. We have some weird instincts that are really counterproductive in water – our [instinctive drowning response](https://en.wikipedia.org/wiki/Instinctive_drowning_response) makes us go vertical in the water and claw upwards with open hands, head thrown back, in a last-ditch effort to keep our mouths above water, which is extremely inefficient and pretty much does the *opposite* of staving off drowning.
* That vertical-in-the-water process is usually silent, too, so if you see somebody like that, don’t think they aren’t drowning just because they aren’t splashing around and screaming for help.
* *Panic* is the natural and all-too-common response to an open-water situation, by most people. When panic happens, instinct takes over, ergo: drowning response, rather than calm, efficient backfloat.
* ETA: **There are more non-swimmers (or non-competent swimmers) than you might think.** A [Red Cross survey](https://www.redcross.org/about-us/news-and-events/press-release/red-cross-launches-campaign-to-cut-drowning-in-half-in-50-cities.html) determined that while 80 percent of Americans say they can swim, only about half of those who claim they can are actually competent – and the bar they used is pretty low. The 5 required skills (which ~65% of Americans **cannot do**) are just:
* Jump or step into water that’s over your head.
* Return to the surface and float or tread water for 1 minute.
* Turn in a circle to find an exit (from, e.g. the deep end of a swimming pool).
* Swim 25 yards to an exit.
* Exit the water.
* Most humans aren’t neutrally-buoyant (“naturally floaty”) in fresh water. Individual people have different densities (more lean muscle mass = denser, generally). Higher density relative the to water = less buoyancy.
* Only about 7% of us naturally float in freshwater at normal lung volume. So even a backfloat requires a bit of effort.
* We’re more buoyant in salt water (up to 69% would float in sea water), which is denser because of the salt, but even regular seawater doesn’t keep everyone afloat all on its own.
* Point being, **even a backfloat takes** ***some*** **energy** and concentration to maintain.
* Waves and currents are a thing. Natural bodies of water aren’t swimming pools. Ever try doing a dead-still backfloat in a public pool when there are kids roughhousing nearby? Kind of hard to do a minimal-effort back float when waves keep washing over your face.
* Bodies of water are nearly always cold, or at least colder than us. Humans need to maintain a constant internal temperature (homeostasis) to function.
* Water has a great capacity to absorb heat and is far more efficient at conducting it away from our skin than air would be.
* You’re therefore unlikely to get hypothermia in 65F air (unless it’s very windy or you’re wet), but you CAN get hypothermia in 65-degree water. You can get some level of hypothermia in 80-degree water if you’re in it long enough.
* This is a big part of the reason you’re hungry and tired after a day of hanging out in the pool, even if you didn’t move around much.
* When you get cold enough, your body closes shunts in the arteries that feed your extremities, in order to keep warmer blood in your core and preserve the function of your primary organs.
* That means your brain stops working well (because it’s apparently not on the list of primary organs). You don’t think so good when you get hypothermic.
* That also means your arms and legs stop getting enough oxygen to actually be capable of movement. Kind of hard to keep swimming when your muscle cells literally lack the fuel to contract.
So, yeah, under perfect conditions you could float for a VERY long time, but not indefinitely:
* If the water was very salty (you’d start to have problems with osmoregulation as saltwater sucks moisture out of your outer layer of skin and mucous membranes (lips and similar) and will eventually break it down completely) and just the right temperature, like in the Dead Sea or a sensory deprivation tank, you’d fix the buoyancy and hypothermia issues.
* If the water was completely calm.
* If you were completely calm, and knowledgeable enough about swimming to do a competent backfloat.
But most drownings occur under much-less-ideal conditions.
There’s a darn good reason [most states](https://www.boatsafe.com/pfd-requirements-state-boating-regulations/) have rules requiring flotation devices for boaters, or at least for children. Even if you panic, and help doesn’t arrive for a long time, it’s a LOT harder to drown if you’re wearing a proper lifejacket.
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