North Atlantic Ocean Eastern Portion

Admiralty chart of the North Atlantic issued when U-boats roamed the seas.

This spectacularly detailed navigational chart covers the entire North Atlantic Ocean between the Gulf of Guinea and the southern tip of Iceland. The British Isles, western Europe, west Africa, the Azores, Cape Verde and Canary Islands are all included within the image; and though primary emphasis is on the water, there is a wonderful amount of interior detail as well. Topography is depicted in hachure, while major rivers, urban centers and coastal landmarks are individually labeled.

Of particular interest are lighthouses and navigational beacons, which are highlighted in yellow and accompanied by their height and visibility. A cautionary note in Algeria warns, “no lights are shown in the Mediterranean east of Gibraltar and Ceuta.” Depth soundings, measured in fathoms, are scattered throughout the image and are often shown with small letters indicating the composition of the seafloor. Currents, seasonal variations, trade winds, and navigational hazards (including icebergs) are also all noted across the Atlantic.

A second note in the upper margin encourages the mariner to “carefully examine and to sound over suspicious appearances before reporting them as positive dangers. The neglect of this practice has led to the Charts becoming studded with imaginary dangers manifestly to the great embarrassment of the Navigator.”

Imaginary dangers were likely the least of the worries of the pilots who may have used this chart, as at the time of publication the North Atlantic was filled with prowling German U-boats. The policy of unrestricted submarine warfare officially introduced in early 1917 was initially very effective at blockading the British coast, but eventually led to the participation of the United States in the war.

This chart was originally published in London by the Hydrographic Office of the Admiralty in 1870, but shows corrections dating to December of 1917.