Water pressure is greater at the bottom of the deep end of the pool when compares to the shallow end of the pool because all of the weight of the water is compressed and pushed down (there is more volume on the deep side).
Think of it like this:
You wear your hat - only 1. It's normal, you only feel the hat fit on. Now imagine that you wear about 10 hats, it starts to feel uncomfortable and after a while, your neck will get stiff due to the pressure of the hats pushing down on your spinal cord. Now imagine 100 hats - the deeper you go, the more pressure is forced on you.