I must admit that it is not easy for me to discuss, in a divine sense, of the Sea. In this perhaps I am, more or less unconsciously, in line with the Roman tradition for which the sea, unlike the Hellenic tradition, has always represented something mysterious, obscure, difficult to understand. Probably, this is due to an instinctive stronger spiritual bond with the "Land Sphere" (Tellus), with the related Divine declinations, compared to the Sea (beware the Sea!).
Being an extremely complex divine dimension, here I will make just few brief considerations which, for this reason, will require future necessary reflections.
The Divine peculiarities of the Sea derive by its inner nature and role it plays within the overall natural structure of Earth. Earth is a huge expanse of water: the Sea. But the mankind cannot use the water of the Sea.
Earth, the human natural space, is a concession of the Sea. The existence of mankind is therefore also linked to this favor the sea gives us. In all traditions there is the image of one or more water-related disasters: the Deluges, representing the alliance of the forces of the Sky with those of the Sea, they are the ways through which humanity is resized, punished in his arrogance, pushed back to a starting point. Mankind is symbolically cancelled by the water as well as for example in the case of Atlantis.
Ancestors were well aware of this representing this condition through the symbolic image according to which the Lands are constantly "surrounded by the embrace" of Oceanus (male polarity) and Tethys (feminine polarity). The waters from the rain (sky) and rivers/lakes (Land) are useful to man, while the sea, from this point of view, remains a world inaccessible to humanity.
The Sea passed by the sun's rays is the sacred space of Poseidon and all his mortal and immortal creatures. Poseidon is a"marine" Zeus whose peculiar symbol is the Trident. This symbol is connected to the primordial tradition and rich in symbols: it is an axial symbolic weapon characterized by very complex meanings and values. It shows such a powerful symbolism that monotheism, to deny its value, put it in the hands of the Devil.
The part of the Sea passed by the Sun rays is a dark and mysterious world tradition assigns as a symbolic space of so-called "primordial Gods/Goddesses". Here there is no space for the Divine Forces that are in some way connected with mankind: it refers symbolically to energies, forces, primordial gods and goddesses of the "Old World". Everything connected to a primal dimension, therefore before the Deities we know, is not extinct, but it is symbolically hidden in the most inaccessible depths of the Sea. The Sea, whose waters are force for future generation (consider Venus for example - energy of the vital "non marine" water but deriving from the Sea) is simoultaneously the place where the most remote and unknown past lies .
The Sea, with its uncontrolled and uncontrollable force, is symbolized by the horse. The impetuous wave of the sea recalls the gait of the horse gallop.
The Traditional Roman Spirituality sacralized the Sea through Neptune. But Neptune remains a not so clear divine force initially connected to the internal waters, then assimilated to Poseidon ... Also Neptune is symbolized by the trident and the Horse. In the Circus Maximus, where horse races were carried out, a big statue of Neptune was placed also for this reason. The same festivities of Neptune, Neptunalia, are festivals about which we know little or nothing.
There would be many other considerations to make, but I stop this post here.