Seven Seas

The International Hydrographic Organization lists over 23 distinct bodies of water called seas.

[5] The modern practice of debating which bodies of water are the seven seas is separate from the etymology of the term.

Plausible etymologies are discussed below including the Po river delta in the north Adriatic sea.

[6] The phrase’s association with the world oceans in the late 19th century is characterized by Rudyard Kipling’s 1896 book The Seven Seas.

The third sea is called Harkand, and in it lies the Island of Sarandib, in which are precious stones and rubies.

The navigable network in the mouths of the Po river discharges into saltmarshes on the Adriatic shore and was colloquially called the "Seven Seas" in ancient Roman times.

Pliny the Elder, a Roman author and fleet commander, wrote about these lagoons, separated from the open sea by sandbanks: All those rivers and trenches were first made by the Etruscans, thus discharging the flow of the river across the marshes of the Atriani called the Seven Seas, with the famous harbor of the Etruscan town of Atria which formerly gave the name of Atriatic to the sea now called the Adriatic.

[13] A history of Venice states: The expression "to sail the seven seas" was a classical flourish signifying nautical skill.

[1] The Babylonian Talmud mentions seven seas and four rivers that surround the land of Israel.

74b, it reads: When R. Dimi came he said R. Yohanan said: "What is the meaning of the verse, 'For he hath founded it upon the seas and established it upon the floods.'

[17] The 17th century churchman and scholar John Lightfoot mentions this set of seas in his Commentary on the New Testament.

Splitting the Atlantic and Pacific into north and south and adding the Southern Ocean returns the list to seven.