https://www.vice.com/en_us/article/n7endd/gravity-anomalies-lead-to-discovery-of-vast-unknown-mountain-ranges-under-the-ocean

Scientists have discovered almost 20,000 underwater mountains on the deep seafloor by examining images of the ocean surface captured from space and looking for gravitational perturbations, reports a new study. 

The research has nearly doubled the number of known “seamounts” from 24,643 to a total of 43,454, while also exposing fascinating details about the topography of the ocean floor and the vibrant ecosystems that thrive on submerged mountain slopes.