This plain, south of Newfoundland, is now known as the Sohm Abyssal Plain. Following this discovery many other examples were found in all the oceans. The Challenger Deep is the deepest surveyed point of all of Earth’s oceans; it is at the south end of the Mariana Trench near the Mariana Islands group.

Abyssal plains are flat areas of the ocean floor in a water depth between 3,500 and 5,000 with a gradient well below 0.1°. They occupy around 28 % of the global seafloor. The thickness of the sediment cover seldom exceeds 1,000 m, and the sediments consist of fine-grained erosional detritus and biogenic particles.

Abyssal plain, flat seafloor area at an abyssal depth (3,000 to 6,000 m [10,000 to 20,000 feet]), generally adjacent to a continent. These submarine surfaces vary in depth only from 10 to 100 cm per kilometre of horizontal distance.

An abyssal plain is an underwater plain on the deep ocean floor. It is usually found 3,000 metres (9,800 ft) and 6,000 metres (20,000 ft) below the surface of the water. Abyssal plains cover more than 50% of the Earth’s surface. They are among the flattest and smoothest places on Earth.

The Abyssopelagic Zone (or abyssal zone) extends from 13,100 feet (4,000 meters) to 19,700 feet (6,000 meters). It is the pitch-black bottom layer of the ocean.

Abyssal Plains The term ‘abyssal plain’ refers to a flat region of the ocean floor, usually at the base of a continental rise, where slope is less than 1:1000. It represents the deepest and flat part of the ocean floor lying between 4000 and 6500 m deep in the U.S. Atlantic Margin.

Animals that commonly occur in abyssal sediments include molluscs, worms (nematodes, sipunculids, polychaetes, hemichordates and vestimentiferans) and echinoderms (holothuroids, asteroids, ophiuroids, echinoids, and crinoids).

The abyssal zone is the deepest layer of the ocean near the seafloor, starting at 13,000 feet and going to about 20,000 feet. This layer of the ocean is incredibly deep and doesn’t get any sunlight from the surface.

6000 to 11,000 meters

Exploration of the Hadal Zone These extreme depths are extremely difficult to study. Fewer people have seen these depths than have been to the surface of the moon! Humans have reached the deepest known point in the ocean, the Challenger Deep, only twice. In 1960 Jacques Piccard and Don Walsh made the first trip.

200 meters

“However we’ve found that in highly oxygenated deeper water, it can be expected that such a body would be skeletonised in less than four days, although bones could be recovered for six months or more.”