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# What is the pressure (in atm) at 300 feet below sea?

I am getting all kind of different information from online sources, such as that every 10 feet below water equals to 1 atm. Is this true? What is the pressure at 300 feet below sea surface?

### 1 Answer

- MugwumpLv 78 years agoFavorite Answer
Hello,

An atmosphere is just the standard atmospheric pressure at sea level. It is equal to 101 325 Pascal. A Pascal is a Newton per square meter.

The pressure under water is simply the density times gravity times the depth (d * g * h)

The density of sea water is about 1025 kg/m^3, I believe.

So if Pressure (P) = d * g * h,

then depth (h) = P / (d * g)

h = 101 325 Pa / (1025 kg/m^3 * 9.81 m/s^2)

h = 10.08 METERS, not feet (That's 33 feet)

Since we are working in metric, lets change your 300 feet to meters

300 feet * .304 m/foot = 91.2 meters

So P = d * g * h

P = 1025 kg/m^3 * 9.81 m/s^2 * 91.2 m * 1 atm/101 325 Pa

P = 9.05 atm

Good Luck