Twice a day, the sea rises up the shore then falls back again
in tides. However, the effect is only local. While the tide
is rising in one place, it is falling in another, as huge forces are
exerted on the vast mass of water in the oceans.
Tides fall in one place and rise in another because the water in
the oceans is moving around, flowing this way and that across the
face of the planet, so that it piles up in one place, making the tide
flow in, and drops away in another, making the tide ebb. It is this
continual ebb and flow of ocean water that makes many simple
explanations of why tides occur misleading or wrong.
