Common types of oceanic landforms include deep-sea trenches, volcanoes, mountain ranges and plateaus. The ocean itself, which encompasses approximately 70 percent of the planet's surface, is considered to be one of the major landforms on Earth.
Landforms are geographical features that characterize a particular terrain or landscape on the surface of the Earth. These formations developed through the continuous activity of natural phenomena, such as erosion, weathering and plate tectonics. Common landforms found on dry land include mountains, hills, deserts, valleys, dunes and plateaus. Bodies of water, such as rivers, bays and seas, are also considered as landforms.
The world's ocean is partitioned into five major water bodies: Pacific, Atlantic, Indian, Arctic and Southern oceans. The oceans are said to have originated after the planet cooled down following its initial formation. Volcanoes ejected enormous quantities of steam into the air, which condensed and precipitated. The torrential rain provided the waters for the planet's primordial seas, which combined and formed the oceans.
Underneath these waters lie an extensive variety of other landforms that are constantly being created and destroyed due to the slow but nonstop movement of crustal plates. The boundary between dry land and sea is called the continental shelf, where it gradually slants down to form the continental slope. Further into the depths of the oceans are the abyssal plain, ridges and volcanic systems. The Mariana Trench, located at Challenger Deep in the North Pacific Ocean, is the deepest point on the planet.