Portunus (alternatively named as Portumnes or Portunes) was a gateway or harbour god symbolized by living and eating mortals, gateways, gates and keys in Roman Mythology.
Portunus who was identified with god Janus looking at past and future at the same time, however who was mentioned as an idiosyncratic god who protected harbours and ensured sailors to return back their home in safety by the Historian Cicero in the course of time, was also watching locations where cereals and foods were kept.
Portunus is known to be pictured with a key in his hand. This term of "gateway/gate" (port) identified with this god gave up its place to the port (as in marine terminology) through changing customs region to region and from mouth to mouth. Portunus had temples and an individual clergy in Tiber located around Aemilian Bridge and Ostia where celebrations were organized for him.
According to the mythological Greek sources, Portunus met another god whom he united with and became god of the ports and gateways. The term "importunes" is used to define unexpected waves and climate conditions in Latin grammar.
The authentic temple dedicated to Portunus for whom a festival called portumnalia is organized on August 16 according to the Roman Calendar is located in Forum Boarium (Boarium Square) in Roma. The keys representing Portunus in the festival organized for him are thrown into the fire to bring luck. Since this temple was turned into church, today it is very well preserved.
What is Portumnalia?
Romans used to organize a visit in August 16 every year in honor of Portunus who was protecting the ports. The name Portunus is derived from "Portunus" (Port) word in Latin, the word "Opportune" is derived from "Ob" (Before) and "Portus" (harbour ) words in Latin and from a combination of "Obportus" (Before Harbour).
Therefore, the vessel arriving the mouth of the harbour symbolizes an "Opportune Moment" (or a Happy moment).
The Roman Temple of Portunus