Abyssal plains are flat or very gently sloping areas of the deep ocean basin floor. They are among the Earth's flattest and smoothest regions and the least explored. Abyssal plains cover approximately 54% of the Earth’s surface and reach depths between 3,000 and 6,000 m (9,800 and 20,000 ft). They generally lie between the foot of a continental rise and a mid-oceanic ridge.


The sea floor is a huge flat area. It lies at depths of about 4000 to 6000 meters below the surface of the ocean. It is called the Abyssal Plain. Sea floor spreading occurs here, which means that there is volcanic action and a mid-ocean ridge where some of the lava has cooled. There are also isolated volcanic mountains called sea mounts, and some black smokers, but most of this area is flat and featureless.