Happy World Ocean Day!
The word ocean appeared in English around the 13th century, crossing the English Channel from France where the Old French word occean predated it by a century of so. The Old French root derived from the Latin oceanus, which in turn came from the Ancient Greek okeanos ( Ὠκεανὸς), meaning the mythical body of water that surrounded the watery world that was Ancient Greece. This was to distinguish it from the Mediterranean and Adriatic Seas which were known to be finite and discoverable. Today we say there are five oceans: the Atlantic, Pacific, Indian, Arctic and Southern, though these are arbitrary and clearly overlap and flow into each other. The world’s oceans contain 1.3 billion cubic kilometers or 310 million cu mi with an average depth of 3,790 meters or 12,430 ft, covering approximately 70% of the earth’s surface.
Image of the ocean by Jeffpro57, used with permission under a Creative Commons 3.0 license.