Today, we will be looking at aspects and regional variations of Poseidon. This is interesting in that the Classical Greek culture was one where the ocean was of much greater importance than you see in other cultures. This is likely to have begun as far back as the Minoan and Mycenaean eras where there are Linear B inscriptions that have been transliterated into something resembling Poseidon’s name. While this is not definitive proof that Poseidon’s worship in the Mediterranean was established that far back, in combination with the wide area where his cultus was found in the Classical period, it certainly points to it being the case.
It can be argued that Poseidon has both oceanic and land-based aspects based on both his epithets and the mythology. He is the ruler of the oceans and has rulership of both calm and stormy seas. But as the creator of horses and also because of there being indications that he may have had a role in the cycle of festivals associated with the Eleusinian Mysteries, there seems to have been a land aspect as well.
As he is potentially seen as an ancestral deity, this would also tend to support a land-based aspect as well.
Most of the regional “variation” that is found is in the minutia of worship. However the largest is that of the variation between the Hellenic and Roman pantheons, Neptunus is the name of the Roman equivalent to Poseidon, but there seems to be some difference in the way the two deities were worshipped in that the Romans seemed to consider Neptunus as being less important than the Greeks did, based on their seeming preference for land-based ventures.