Neptune  god of fresh water and irrigation.

 
Neptune was originally the minor god of fresh water and irrigation.

It wasn't until the Romans identified him with Greek Poseidon (399 BC), that he became the great god of the sea. His consort was Salacia (possibly Amphitrite). Neptune was also equated with Nethuns, the Etruscan god of fresh water and well.

His festival, Neptunalia, was held on July 23, and his temple was found in Circus Flamminius, Rome.

In astronomy, the 8th planet from the sun, and the 4th largest planet in our solar system. The planet is blue in colour, due to high concentration of methane gas in its atmosphere; as well as hydrogen and helium. Like the other giant planets, it has rings. There are at least eight satellites in Neptune's orbit; the largest moons are Triton and Nereid.