The Romans borrowed many of their gods from their neighbors. The sea god Neptune is a mix of Poseidon (Greek) and Nethuns (Etruscan.) He was the brother of Jupiter and of Pluto. After the defeat of their father Saturn, the three brothers divided the world in three parts to be ruled by one of the three brothers. Jupiter took the sky, Neptune the sea and Pluto the underworld.
Like Poseidon, Neptune was also worshipped by the Romans as a god of horses, under the name Neptune Equester, patron of horse-racing.
In 2007 an A.D. 300, 5.9 foot marble statue of Neptune was found in the in the Rhone River. This is just one of the many exciting things found by these archeologists. I've been looking for pictures of the statue, but have yet to find any.
From Wiki -
"King Neptune" plays a central role in the long-standing tradition of the "Line-crossing ceremony" initiation rite still current in many navies, coast guards, and merchant fleets.
When ships cross the equator, "Pollywogs" – sailors who had not done such a crossing before – receive "subpoenas" to appear before King Neptune and his court (usually including his first assistant Davy Jones and her Highness Amphitrite and often various dignitaries, who are all represented by the highest ranking seamen).
Some Pollywogs may be "interrogated" by King Nepture and his entourage. At the end of the ceremony – which in the past often included considerable hazing – they are initiated as Shellbacks or Sons of Neptune and receive a certificate to that effect.
Sounds very swishy! I'd love to see some pictures of that!