Sea water has a pressure of .44psi per ft. or 4.4psi per 10'. Therefore at a dpth of 300' there would be 132psi correct? At 200' feet down there would be 88psi yes? Now the question (please don't laugh) If I had a tube with a metal ball in it, sealed at one end like a test tube, that was 100 feet long and I placed the bottom of it at 300' down, leaving the top (open) at 200' down - Would the pressure on the the ball at the bottom of the tube be the same as if I had just placed the ball in the open on the ocean floor? There would be the weight of 300' of water pushing down on the ball in the tube, but there would not be the SURROUNDING pressure on it because THAT pressure would be on the tube... maybe What if the tube was full of water but ran all the way to the surface? Would ball A (the one in the tube) have less pressure on it than ball B (the one in the open on the seafloor) ?