You would think that with such powerful search tools like Google, that question would be relatively easy to answer. Try it. If your search was anything like mine, you found a confusing collection of partial answers, none of them correct!
Take the Library of Congress’ Science facts page entitled “Everyday Mysteries.”
“Not all geographers agree on this list of seven, believing that the seven seas reference will be different depending upon the part of the world and the time period in question.
Some geographers point to the Age of Discovery and suggest that the seven seas represent the Atlantic, Pacific, Arctic, and Indian Oceans, as well as the Mediterranean Sea, the Caribbean, and the Gulf of Mexico.” 
Now if we’re worth our salt, we know the difference between an Ocean and a Sea, right?
The Seven Seas are referred to in the literature of the ancient Hindus, Chinese, Persians, Romans and other nations. In each case, the term simply referred to different bodies of water. Sometimes it even referred to mythical seas. To the Persians, the Seven Seas were the streams forming the Oxus River; the Hindus used the term for the bodies of water in the Punjab. There is a group of salt-water lagoons that separated Venice, Italy from the open sea, that the Romans called septem maria, the Latin phrase for Seven Seas.
Still the debate continues. Even the renowned Woods Hole Oceanographic Institution got it wrong, as I found on their website,
“To the ancients, ‘seven’ often meant ‘many,’ and before the fifteenth century, the many seas of the world were:
- the Red Sea
- the Mediterranean Sea
- the Persian Gulf
- the Black Sea
- the Adriatic Sea
- the Caspian Sea
- the Indian Ocean
The Portuguese were actually the first European power to come into contact with India when Vasco de Gama sailed into Calcutta in 1498. After that date, Portuguese ships would frequently return to Europe laden with spices and commodities that would fetch fabulous prices. Other European powers looked enviously at this stream of exotica coming from the Orient. Portugal managed to hold on to its preeminent position largely in part to the Treaty of Tordesillas of 1494. This treaty had been created to divide the New Worlds between the Catholic countries of Portugal and Spain. In effect they had carved up these New Worlds with Spain receiving a monopoly of power in most of South America and Portugal in the Indies. Working together, the two Catholic countries were able to maintain an effective blockade of these new markets for the majority of the sixteenth century.
Ships would always prove to be a more economically viable way of trading with India. And, as the English could not directly trade with India, its sailors resorted to buccaneering and piracy of the Portuguese ships as they headed to Europe with their valuable cargoes. It was with the era of Drake and Cavendish looting and shooting their way around the world that the first cracks appeared in the Catholic monopoly. In fact, it was Drake’s victory over the Spanish Armada in 1588 that really opened the floodgates. The Navies of the Catholic countries were no longer strong enough to ensure an effective blockade of their New Worlds. English and Dutch ships began to pass the Cape of Good Hope in increasing numbers. Both nations quickly established Chartered companies to exploit the commercial possibilities presented to them. The English East India Company was established in 1600. The EIC would lead the vanguard for British political power in India. The EIC sent many a clipper ship across the “Tea Route” to China and back.
According to Peter Freuchen, in Book of the Seven Seas, “The Seven Seas” is a very old phrase and a very new one, too. In between nobody tried to count. The Ancients of the Mediterranean world knew seven large bodies of water, so they thought these were all the seas of the world. For a long time people were content with this, but when the age of exploration began, they learned that the Ancients had made a little mistake. There was not only a lot more water than they believed, but men were going out and finding great new seas all the time, and giving them names. So the expression “Seven Seas” dropped out of use for many centuries.
It came back in 1896. That year Rudyard Kipling was looking for a title for a new volumn of his poems. He selected The Seven Seas, and because he was a great man, and a popular man, the world had to make his words good. So the geographers figured out a way to divide the ocean into seven parts. It isn’t a very good way, but we get along with it even if few of us can remember what the seven are. The whole thing is a triumph of poetry over reality.
The Seven Seas
In Antiquity Today
China North Atlantic
West African South Atlantic
East African North Pacific
Indian Ocean South Pacific
Persian Gulf Indian
So the phrase was popularized by Rudyard Kipling who used it as the title of a volume of poems first published in 1896. Kipling himself said the term might be regarded as referring to the seven oceans (named above) even though it was a very old figurative name for all the waters of the world.
It follows then, that the notion of an “Old Salt” is one who “has survived the Seven Seas” was coined to describe just such a sailor: One who sailed with the East India Company for more than a few voyages.
So, to settle this debate, I put forth that The Seven Seas are, and always have been…
1. The South China Sea
2. The Celebes Sea
3. The Timor Sea
4. The Banda Sea
5. The Flores Sea
6. The Java Sea
7. The Sulu Sea
Any old salt who had “sailed the Seven Seas” proved he had been on the old “Clipper Ship” tea route from, China to England, which was the longest trade route under sail and which took the Clippers through any or all of those Seven Seas.
Now, aren’t you glad that we straightened that out?
Of course, it is of no real consequence these days. Take The Seven Seas Cruising Association… one can join even if you’re not sailing an old clipper ship. For over 50 years, SSCA has recognized the major sailing accomplishments of regular folk like you and me and reward such. Members who cross major bodies of water (oceans) may receive the “Trans-Ocean Award.” Those who complete one, may receive the “Circumnavigation Award.” The SSCA is the oldest Association of its kind in the world, and still the largest. Its’ members are from all over the globe. All are welcome!
Just like in the days of yore, SSCA recognizes that becoming an accomplished sailor has its merit. So, whether you’ve sailed the Seven Seas, have just cruised the Caribbean for a few seasons or are planning to someday, you will be among the proud, if not salty, group of time-honored sailors when you join the Seven Seas Cruising Association. For more information about membership and to join, visit www.ssca.org or call: 954/771-5660.
 Book of the Seven Seas by Peter Freuchen, with David Loth