http://www.sciencemag.org/news/2019/11/trump-plan-push-seafloor-mapping-wins-warm-reception

The National Oceanic and Atmospheric Administration mapped the sea floor in the Central Pacific Basin, including a 4200-meter-high mount called Kahalewai.

The coastal waters of the United States cover an area dwarfing the nation itself. Yet more than half of that ocean floor is a blank—unmapped by all but low-resolution satellite imagery.