Volcanology that Hephaestus, the god of fire, sat below the volcano Etna, forging the weapons of Zeus. The Greek word used to describe volcanoes was "etna", or "hiera", after Heracles, the son of Zeus. The Roman poet Virgil, in interpreting the Greek mythos, held that the giant Enceladus was buried beneath Etna by the goddess Athena as punishment for rebellion against the gods; the mountain's rumblings were his tormented cries, the flames his breath and the tremors his railing against the bars of his prison. Enceladus' brother Mimas was buried beneath Vesuvius by Hephaestus, and the blood of other defeated giants
The God Beneath the Sea Eurynome and the two goddesses tell him various Greek creation myths. The novel continues with myths of the Olympians and the age of gods and mortals, and concludes with Hephaestus returning to Olympus, having been cast down for a second time after reproaching Zeus. Garfield, Blishen, Keeping, and Longman collaborated on a sequel entitled "The Golden Shadow" (1973, ). It is based on myths of the later heroic age, when divine activity was limited. "The God Beneath the Sea" is divided into three parts. Part one begins with the image of the infant Hephaestus plummeting from Olympus to the ocean.