sealock

plural sealocks

1. A lock that is positioned at the mouth of a canal or waterway so that, when the gates are closed, boats can be raised or lowered between the waterway and sea level.

   All masters are prohibited from approaching the entrance to the sealocks when they observe a red flag flying […]

   1951, United States. Defense Mapping Agency. Hydrographic Center, Sailing Directions for the West Coast of Scotland: Mull of Galloway to Cape Wrath Including the Hebrides, page 127

   2 more examples

   At Corpach it is intended to form a sealock, to be cut out of the rock, and to make a small basin within it, capable of admitting a number of vessels with the flowing tide, which, after the gates are closed, may ascend the locks at leisure, […]

   1809, Sir John Carr, Caledonian Sketches, Or, A Tour Through Scotland in 1807, page 224

   Ardrishaig, situated about halfway up Loch Gilp on the west shore, marks the entrance to the Crinan Canal, which is entered through the sealock behind the breakwater.

   2020, Clyde Cruising Club, Geoff Crowley, Firth of Clyde: Including Solway Firth and North Channel, page 77

   Synonyms: tidal lock

plural Sealocks

1. A surname.