abyssal hill

An abyssal hill is a small hill that rises from the floor of an abyssal plain. They are the most abundant geomorphic structures on the planet Earth, covering more than 30% of the ocean floors. Abyssal hills have relatively sharply defined edges and climb to heights of no more than a few hundred meters. They can be from a few hundred meters to kilometers in width. A region of the abyssal plain that is covered in such hill structures are termed an "abyssal-hills province". However, abyssal hills can also appear in small groups or in isolation.