The remarkable Lost City hydrothermal vent field, so named partly because it sits on a seafloor mountain named the Atlantis Massif, was discovered in the middle of the Atlantic Ocean about 1,500 miles off the East Coast of the United States during an expedition that wasn’t even looking for hydrothermal vents. Now the two scientists who were the first to travel in a submersible to the field after its serendipitous discovery Dec. 4, 2000, are leading a National Science Foundation-funded expedition to map and farther investigate the field.