The pressure at the bottom of the ocean is just equal to the weight of water above you. So every 1ft of tides produces about half a psi of pressure change (or 1

The pressure at the bottom of the ocean is just equal to the weight of water above you. So every 1ft of tides produces about half a psi of pressure change (or 1 meter and 1000 Pa). My guess would be that the water doesn't matter so much, but what they're talking about is tidal bulges in the earth's crust and mantle.