I did my research and the answer I got is deeper I go the more weight from the water above me that I have to handle just like lifting weight. Like in the picture below It is reasonable that I will feel the pressure on the top of my head and on the upward side on my arms ( like in the picture) due to the effect of the gravity pulling the water down. But how can I still the pressure everywhere else like on the bottom on my legs, my left side body, every single point on my body. Gravity can't pull the weight upward right? my little theory is the water molecules have something to do with this. Since they moving around rapildly. they will crash into our skin molecule (our body molecule) and create pressure. I hope you guys can explain this to me. Thank you.