Scuba Diving Pressure: Understanding ATM and Depth

Question
I have been told an "Atmospere" in scuba diving is 33 feet deep, (2 atmosperes being 66 feet, etc). I have not been able to find anything varifying this. Can you tell me if these are true statements? Thank you.

Answer
Jeff,

For ocean water that is correct.  In fresh water, one Atmosphere (ATM) of pressure is equal to 34 feet of water.

This is from the Office of Naval Research:

http://www.onr.navy.mil/focus/ocean/water/pressure1.htm

Thanks for the inquiry,

Henry Babcock
AllExperts SCUBA Expert