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A classic movie threat: quicksand that will ensnare you and kill you by drowning.

Still from Indiana Jones and the Kingdom of the Crystal Skull

[Still from Indiana Jones and the Kingdom of the Crystal Skull]

It's in countless movies and TV, but does quicksand pose any significant life-threat to people? Is the best strategy to hold still (as opposed to just try to walk or swim away, that is)?

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Quicksand isn't nearly as deadly as the movies would have us believe. You can be killed in it, but if you behave sensibly then you shouldn't find any trouble getting out.

Quicksand is, essentially, a mix of sand and water. That means it looks like sand, but when you step on it you sink into it like water. However, by definition, it's denser than water, and that means two things: 1) you sink into it less quickly than you would if you stepped onto water 2) you can float in it, or swim - more easily than water in fact. The problem comes because quicksand is very sticky (viscous) and if you step in it, it can be hard to pull yourself out.

Here is a National Geographic article giving the science, and an explanation of how to get out of quicksand if you end up in it.

If you do step into quicksand, you'll only sink in a little deeper than your waist. "I would say there would be some pressure on the chest, but not enough to cause serious trouble." So how do you get out? "The way to do it is to wriggle your legs around. This creates a space between the legs and the quicksand through which water can flow down to dilate [loosen] the sand. You can get out using this technique, if you do it slowly and progressively."

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    i was once told qucik sand was very fine sand, hence the reason you could get sucked into it. never heard the sand water combo before. found what i was told en.wikipedia.org/wiki/Dry_quicksand the wiki even states that this is where indi sinks in and that indi explains the diffrences between dry quicksand and the normal one you have in your post. – Andy May 25 '11 at 15:40
  • This matches what I heard from some of these "Survival in the wild"-shows (can't remember the name). In Summary: You don't go under the full way in (wet) quicksand because its twice as dense as you. You have a good chance to get out. One bigger issue is that the wet sand stops you from sweating which will lead quickly to some heat stroke in hotter regions. Maybe not in the jungle as shown in the picture above, but in the desert I can see that this is quite deadly. – Martin Scharrer May 25 '11 at 17:28
  • @Martin would it be possible to have a water mixture in a desert though? i mean based on my ideas of a desert, water would quite quickly evaporate and just leave sand. – Andy May 25 '11 at 18:33
  • @Andy: It should be possible to have wet spots even in the desert. There might be some underground water source ... – Martin Scharrer May 25 '11 at 18:36
  • Isn't part of the problem with quicksand is that it's a non-Newtonian fluid that is shear thickening, i.e. when you shear it its viscosity increases. This means that as you struggle to get out, the quicksand becomes less liquid and therefore harder to escape. – Alan Munn May 26 '11 at 22:20

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