The Trump administration is considering rolling back federal protections for a number of national monuments. While most are on land and relatively accessible, three are deep below the ocean’s surface and many miles from the mainland: the Pacific Remote Islands Marine National Monument and the Rose Atoll Marine National Monument, both in the central Pacific Ocean, and the Northeast Canyons and Seamounts Marine National Monument off the coast of New England. While most people will never explore the canyons and reefs of these watery realms, their value is hard to overestimate, according to Stanford scientists with years of experience exploring and studying these and adjacent areas.