The Weight of Water

Every time I think of submarine, I think Sean Connery. At the top, why can't the water just be like that? It'd be so much nice. The farther down you go, you have the weight of the water weighing you down. There's 10 pounds on a 21 foot vessel that's sealed right now and it weighs around 4 to 5 pounds per person. One human poops about 20 times every day since Sunday - an average of 1lb 6oz.