Asphaleius or Asphalius (Ancient Greek: Ἀσφάλειος or Ancient Greek: Ἀσφάλιος) was a cultic epithet of the Greek god Poseidon,[1][2][3][4] under which he was worshipped in several towns of Greece, such as at Taenarum, Kalaureia, and Sparta, but also across the wider Greek world.[5][6][7][8] His Greek name may also be transliterated as Asphaleus, Asphaleios, or Asphalios.
In Greek, asphaleia means "safety", or an absence of instability.[8] This epithet broadly describes him in a protector role, as the god who grants safety to ports and in sea navigation in general, a "guardian of the harbor".[9][10]
In this aspect he was also a "bringer of stability", both in the personal sense, as a cane or walking stick might make an old man more stable, as well as in a more concrete sense, as in the stability of war fortifications. The Erythraeans regularly sacrificed to Poseidon Asphaleius to protect the city's walls, as did the Colophonians when in the 4th century BCE they built new fortifications for their town.[8] We also have evidence of several ancient inscriptions that urge townspeople to sacrifice to Poseidon Asphaleius in the aftermath of an earthquake, to bring stability back to their town.[11]
There are ruins of an altar to this aspect of the god on Aigai.[8] The still extant Temple of Poseidon on Tainaron is dedicated to this aspect of the god.