- waterline, water line, water level - a line corresponding to the surface of the water when the vessel is afloat on an even keel; often painted on the hull of a ship
--1 is a kind of line
--1 has particulars: load line, Plimsoll line, Plimsoll mark, Plimsoll - water line, watermark - a line marking the level reached by a body of water
--2 is a kind of line
--2 has particulars: high-water mark; low-water mark