There are three undersea canyons within the monument: Oceanographer, Gilbert, and Lydonia canyons. These canyons are among the largest of about 35 major undersea canyons that line the U.S. continental shelf edge from Cape Hatteras north to the Canadian boundary. From the lip of Oceanographer Canyon to its deepest location, the canyon is approximately 4,000 feet deep. This is the average depth of the Grand Canyon!
The canyons are cut into the continental slope and lower continental shelf. They have steep walls and are largely formed by erosion on the continental slope.
Upwellings of deep, cold water around the canyons bring nutrients that support large quantities of plankton, krill, forage fish, and schools of squid, which in turn, nurture high abundances of large marine animals such as, whales, dolphins, and large migratory fish.