Waves at high tide crash on shore near Kalbarri National Park in Western Australia.
These would trap water at high tide and release it later through electricity-generating turbines.
My brother bought a pig in a poke. He bought some property in Florida over the phone. It was on the ocean - in fact at high tide it was six feet under water.
Going down to the sea in ships is easy enough with gravity's help, but at high tide the ascent upon arrival gives the legs a good mountain work out.