I want to know how much work it is to move a certain volume of water at a certain depth. For instance, take a submarine at 300 meters depth and I want to have the submarine extend out an arm from inside. the Arm is 1 meter by 1 meter by 5 meters long. Thus the volume of water displaced is 5 meters cubed. At 300 meters the pressure of water is about 3750 Kilopascals. Since we have the formulas: p=f/a W=f * d the mass of the water is 5000kg and the force is then 5000*9.81 =49050 newtons? but how do i incoporate the pressure at this depth? Certainly pushing this mass 1 meter over is easier on land then in such a high pressure?