The seashore—also called the coastline, shoreline, or beach—is that portion of a continent or island where the land and sea meet. The seashore includes the area covered by water during high tide and exposed to the air during low tide, the area splashed by waves but never under water, and the area just beyond the shore that is always under water. (The tides are the rhythmic rising and falling of the sea.) Seashores vary greatly in appearance, from flat and sandy and washed by gentle waves to storm-battered and rocky or bounded by tall cliffs.