I came to know that we don't get crushed by the atmospheric pressure because our blood vessels have become accustomed to applying the same pressure and the net effect ultimately cancels out.

Now let us assume that I got $10m$ under water which ultimately leads to a pressure of $2$ $atm$ on me, meaning an extra pressure of $1$ $atm$ over me. Thus a force of $1$ $atm$ would be squeezing me from ever side. Won't I be just crushed down at that point from all sides just like a can having no air inside is crushed by the atmospheric pressure outwards.

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    $\begingroup$ Why crushed? Squeezed for sure - deep-sea divers have a hard time breathing because lungs are pressed upon and as I remember from just 4 meters in swimming class the pressure is easily felt on your skin as well - but "crushed" sounds like bones breaking and lungs collapsing... The amount of pressure that bones and body can withstand might be worth a googling. And I believe the value is far deeper than just 10 meters, since world-records of free deep-diving has gone further that 60-80 meters or so as far as I know. There are issues with bobles in blood veins, but "crushing" is a bit dramatic $\endgroup$ – Steeven Oct 14 '16 at 11:46
  • $\begingroup$ @Steeven nah not at all you don't feel any kind of pressure on you in 30 meters (apart from your ears etc. see my answer) and breathing is not a problem either because if you are breathing from an air tank (usually filled around 200 bar) with a regulator there are absolutely no difference in the way you breathe (since that is the job of a regulator). $\endgroup$ – Gonenc Oct 14 '16 at 12:03
  • $\begingroup$ @gonenc Point taken. How depths feel after evening out the pressure in lungs and ears is not something I would know of. Good answer. $\endgroup$ – Steeven Oct 14 '16 at 12:51

Well nothing really to your body. I'll assume that at $10\, \mathrm m$ the pressure is roughly $1\, \mathrm{atm}$ (not quite but close enough.) The reason is that you are mainly made out of liquids and solids. Like your muscles and bones and spinal fluids etc. From high-school you might know that you can compress liquids very little e.g. the compressibility of the water is around $10^{-10}\, \mathrm{Pa}$, whereas you cannot (practically) compress solids at all. From the approximate equation:

$$\frac{\Delta V} {V}= - \beta \Delta p$$

where $\beta$ is the compressibility you get for $\Delta p=1 \, \mathrm{atm}\approx 1 \cdot 10^{5} \,\mathrm{Pa}$ you get for a change of volume of water

$$\frac{\Delta V} {V}= - 10^{-3} \% $$

I guess $10^{-3} \%$ is quite a negligible change.

There are however some exceptions, namely your lungs and your ears (and your mask if you have one), which are confined spaces filled with air. Roughly in $5 \, \mathrm m$ you start feeling the pressure on your ears, since your eardrum is pretty sensitive on small changes and your lungs doesn't pose a problem if you are breathing from an air tank (like when you are scuba diving) since the regulators, form which you breath air adjust the pressure in such a way that you can breathe just normally as if you were on the surface. I've been regularly scuba diving (~$30 \, \mathrm m$) for some time and you really don't feel the pressure on you apart from these exceptions.

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