This 26 August 2018 video from the USA says about itself:
Scientists Discover Giant Deep-Sea Coral Reef Off Atlantic Coast
This is a huge feature, Cordes said. It incredible that it stayed hidden off the U.S. East Coast for so long.
DEEP-SEA CORAL REEF FOUND IN ATLANTIC Scientists have discovered a giant deep-sea coral reef some 160 miles off the coast of Charleston, South Carolina, and a half-mile below the ocean surface. [HuffPost]
This 1914 video says about itself:
More than 70 underwater canyons exist off the northeastern coast of the US, some more than three miles deep. In this video, journey to the deep and discover new species of deep-sea coral and more through the eye of a remotely operated vehicle (ROV).