Ok stupid question I know but I'm probably just thinking about it all wrong. If I have a container that can't be compressed in any way filled with air and I bring it to the bottom of the sea why would the air pressure inside increase? The way I'm thinking is that it is separated from any outside pressure and therefore the pressure shouldn't change, I know it does but I don't understand how if this container can't be compressed. I know if I brought the same container up a mountain there would be less pressure but still don't know why. Someone was trying to tell me the weight of the atmosphere presses down on the container but like I said if it can't be compressed how does the outside atmosphere effect the inside pressure? Like I said I am probably thinking of it all wrong, I'm thinking of it as a force pushing on something. Like if I took that same container and put a few boulders on it the pressure inside wouldn't change so why would it change with the weight of the atmosphere or water on top? I was talking about this with a physics student and I guess I just didn't get the answer and I'm now curious. Thanks.