Rock which does not cover,
Coral reef, detached,
Wreck always partially submerged.
A number of sunken wrecks,
Obstruction of any kind,
Limiting danger line.
Foul ground, discolored water,
Old map symbols and their descriptions can be poetic, enjoyable to view and read while providing ideas for symbols on contemporary maps. Indeed, is it possible that “maps are poems and poems are maps?” (see Howard Veregin’s “Geo-Poesy.”
Good map designers and map makers always look at other maps, including old maps, for map design ideas.
These symbols and textual descriptions of nautical dangers are taken from section O of Chart #1, Nautical chart symbols and abbreviations used by U.S. Lake Survey, Corps of Engineers, U.S. Army, Dept. of Defense; U.S. Coast and Geodetic Survey, Dept. of Commerce; U.S. Navy Hydrographic Office, Dept. of Defense (Washington DC, 1957). The entire page O from which the symbols were taken is here. A contemporary version of these symbols, still Chart #1, is here.