On September 15, 2016, President Obama designated the first marine national monument in the Atlantic Ocean. The Northeast Canyons and Seamounts Marine National Monument includes two areas: one that includes four undersea mountains, called “seamounts” – Bear, Mytilus, Physalia, and Retriever; and an area that includes three undersea canyons – Oceanographer, Lydonia, and Gilbert – that cut deep into the continental shelf. These sea features have monumental histories.

Coast Survey cartographer Leland Snyder used several data sources to create this map of the Northeast Canyons and Seamounts Marine National Monument.

Bear, Mytilus, and Physalia Seamounts were discovered by oceanographers with Woods Hole Oceanographic Institution, and they were named for small Woods Hole vessels that began making forays into the deep sea in the 1950s. The Bureau of Geographical names does not know the origin of the name “Retriever Seamount,” but NOAA historian Skip Theberge thinks it was probably discovered and named…