The oceanic ridge is the site of frequent earthquakes. Volcanism is common in ocean ridges and it produces many relief features.
Scattered over the entire sea floor are thousands of submerged volcanoes with sharp tops called seamounts.
The oceans, unlike the continents, merge so naturally into one another that it is hard to demarcate them.
The Pacific, the Atlantic, the Indian and the Arctic. The various seas, bays, gulfs and other inlets are parts of these four large oceans.
A major portion of the ocean floor is found between 3-6 km below the sea level.
