The Neptunalia venerates the divine God of the Sea, Neptune. Originally a freshwater God, Neptune acquired his maritime status when we was identified with the Greek Poseidon At Rome, there was a temple dedicated to Neptune in the circus cus Flaminius within the Campus Martius where his festivals were held on July 23 and December 1.
Neptune was one of only three Gods to whom a bull might be sacrificed (the others were Mars and Apollo). According to legend, he had a wife whose name was Salacia, Goddess of the salty sea and inland guardian of springs. It is believed that the Goddess Sulis, who is still worshiped at the sacred hot springs at Bath, may have been an aspect of Salacia.
Mighty Neptune, may it please,
Thee, the Rector of the Seas.
That my Barque may safely runne,
Through thy watrie-region;
And A Tunnie-fish shall be,
Offer’d up, with thanks to thee
—Robert Herrick, “To Neptune, Hesperides” (1648)