> I was just curious about how long the air lasts in a #80 tank...I know
 > it depends on how deep you go..but can anyone give me some sort of an
 > idea if the dive stays around the 30' range...
Anthony, a lot depends upon your SAC (Surface Air Consumption) rate.  For me, 
I can last around an hour with no problem at 30 feet.  Others I know, can do 
the same dive and make it last 2 hours.
It all depends upon the size of the individual and his comfort level in the 
water.
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