A sheet of salt water separated from the open sea by sand, shingle banks or a road embankment. The sheet of water between an offshore reef, esp. of coral, and mainland. The sheet of water within a ring or horseshoe shaped atoll.
Data Dictionary for lagoon_poly: https://docs.topo.linz.govt.nz/data-dictionary/tdd-class-lagoon_poly.html
This layer is a component of the Topo50 map series. The Topo50 map series provides topographic mapping for the New Zealand mainland, Chatham and New Zealand's offshore islands, at 1:50,000 scale.
Further information on Topo50:
http://www.linz.govt.nz/topography/topo-maps/topo50
