Ape Man in a movie is shown evading his captors by hiding underwater for many minutes while breathing through a long reed. Assuming the maximum pressure difference lungs can manage and still breathe is -80 mm-Hg , calculate the deepest he could have been. I immediately thought of P = p*g*h, where p = density. h is the depth, but this is for gauge pressure. Do I use the formula for absolute pressure P = atmospheric pressure + pgh? Am I correct in my reasoning? Thanks.