From Longman Dictionary of Contemporary Englishwaterlinewa‧ter‧line /ˈwɔːtəlaɪn $ ˈwɒːtər-, ˈwɑː-/ noun 1 → the waterline2 [singular] the edge of a large area of water, especially the sea, where it joins the land As the waterline advanced, the vegetation was swamped.
Examples from the Corpus
waterline• There are entrances at different levels, including some below the normal waterline for use in emergencies.• There the trouble is largely above the waterline, though.• The third struck above the waterline setting fire to the aircraft fuelling system ruptured by the first two hits.• Two of the torpedoes struck below the waterline on the port side near the aviation fuel tanks.• Her machinery and her accommodations for equipage and her fifty-eight-man crew were below the waterline.• The boat burns to the waterline and sinks, leaving no surviving witnesses or evidence. 