All continents are on water

I think that the center of earth is all water and under us is all water.

Because earth consists mostly of water at the surface but we havent been to the very bottom of the ocean.

And because of all continents are on water and maybe there is some big sea creatures deep deep down, they are making earth quakes.

And the pressure must be really really strong so deep and maybe that makes the gravity.

(this just something that have come to mind, and english is not my first language so have that in mind)