1. The problem statement, all variables and given/known data The human lungs can function satisfactorily up to a limit where the pressure difference between the outside and inside of the lungs is 1/20 of an atmosphere. If a diver uses a snorkel for breathing, how far below the water can she swim? Assume the diver is in salt water whose density is 1029 kg/m3. 2. Relevant equations 1 atm = 1.013e5 Pa 1/20 atm = 5065 Pa P1 + P2 = gauge pressure P = density*gravity*height P = Force/Area 3. The attempt at a solution So the pressure in the lungs minus the pressure outside the lungs must be less than 5065 Pa. If P1-P2 = 5065 and P2 = 1029*height these should just be combined somehow. However, how do I know what the pressure is inside the lungs? If I use 1 atm, 1.013e5 - 1029(g)(h) = 5065 96235 = 1029(9.8)(h) h = 9.54 m But this is not correct. Does anyone have a suggestion?