Rio Bidasoa to Cape Penas

Post-WWI coastal chart of northern Spain along the Bay of Biscay.

This fascinating navigational chart was published by the Hydrographic Office of the United States Navy and updated to 1919, according to the rubber stamp in the upper left. It covers a large coastal region of northern Spain and western France between Cabo Penas (near Gijon) and Bayonne.

Interior details are confined largely to contoured topography (which could be helpful as identifiable landmarks from sea), place names, and a handful of railways. Lighthouses are highlighted in yellow dots, though a cautionary note warns the reader; “many of the lights on this coast are, besides being weak, placed so high as to be frequently obscured by mist and so give the mariner little warning.”

Within the Bay of Biscay, depth soundings in fathoms are often accompanied by a small letter which indicates the composition of the seafloor; important information when considering dropping anchor. The locations of navigational buoys and various hazards are noted, and three compasses assist with calculating the variation in magnetic delineation.