The Arctic, North Atlantic, South Atlantic, North Pacific, South Pacific, Indian, and Southern Oceans are the regarded as the current Seven Seas.
Ancient cultures dating back to 2300 BC also identified the Seven Seas, using bodies of water that were culturally or economically significant.
The Seven Seas has changed meaning over the course of history since it was first used in Sumerian literature around 2300 BC. At that time, it appears that the reference may have been more metaphorical than literal.
Persians, Romans, Arabs, and Phoenicians had their own definitions of the Seven Seas. For detailed information, I suggest having a look at a great article put together by Live Science – What Are the Seven Seas?.
The more widely recognized early description of the Seven Seas comes from the ancient Greek literature where they were understood to be the Aegean, Adriatic, Mediterranean, Black, Red, and Caspian seas and the Persian Gulf.
Medieval Europeans regarded the following as the Seven Seas; North Sea, Baltic, Atlantic, Mediterranean, Black, Red, and Arabian seas.
After Europeans ‘discovered’ North America, the concept of the Seven Seas changed again. Mariners then referred to the Seven Seas as the Arctic, the Atlantic, the Indian, the Pacific, the Mediterranean, the Caribbean, and the Gulf of Mexico.
Today’s definition of the Seven Seas has been adapted to reflect the more global perspective of modern society and is really just a list of the oceans of the world. Since there are 5 oceans (Arctic, Atlantic, Pacific, Indian and Southern), the Atlantic and Pacific have been split into two each as a matter of convenience so the total adds up to 7.
In this humble author’s opinion, that’s cheating and we may as well just say the “Sail the Five Seas” instead.
It’s hard to imagine that each of the ancient and modern societies had exactly seven bodies of water that were culturally or economically important. The tweaking of the modern definition to include Northern and Southern Oceans demonstrates that we fit the selection of the seas to the fit the phrase rather than the other way around.
Historically, culturally, and religiously, the number seven is a very significant number. Isaac Newton identified seven colors of the rainbow, there are Seven Wonders of the ancient world, seven days of the week, … the seven-day story of creation, the seven branches on a Menorah, seven Chakras of meditation, and seven heavens in Islamic traditions — just to name a few instances.
What is a sea exactly?
In addition to the number being somewhat loosely applied, it feels as though calling each body of water a “sea” is a little bit loose as well. So, let’s take a moment to look at what the modern definition of a sea is.
Merriam-Webster offers the following as one its the definitions – “a body of salt water of second rank more or less landlocked”, but also “an inland body of water”. Oxford makes no reference to salt water and simply says “A roughly definable area of the sea.” or “a large lake”. Both dictionaries give as their first definition a description of the broader ocean system that covers much of the earth – e.g. “The expanse of salt water that covers most of the earth’s surface and surrounds its land masses.”
Well I guess, the Adriatic, the Persian Gulf, the Carribean and the North Atlantic and others are roughly definable areas of the sea, but only some are more or less land-locked bodies of salt water. Fair enough.