strand, beach, shore
渚 centers on the edge of water meeting land: a beach, shore, or strand where waves wash up.
渚 combines 氵 (water) with 者, which likely contributes the sound. Together they suggest a place where water meets land.
Water 氵 beside 者, like a person standing at the water's edge: 渚 is the shore or beach.
For ショ, imagine a show being performed on the beach: show -> ショ, and the waves are the audience.