Fall 2009 » UA Q & A » What is the difference between an ocean and a sea?

October, 2009

Steve K. Boss, associate professor of geosciences, replies:

In a literary sense, these two words are frequently used interchangeably. Indeed, there is relatively little distinction between them. The seas of our world are actually parts of the ocean, with a few exceptions such as the Caspian Sea and the Aral Sea.  In general, seas are parts of the ocean that may be surrounded or nearly surrounded by land, such as the Mediterranean Sea, Black Sea or Red Sea.  However, the water in seas is of similar chemical composition to water throughout the world ocean -- for example, it is salty -- and the biota found in seas is also similar to that found elsewhere in the ocean.