According to folk etymology, Deucalion's name comes from δεῦκος, deukos, a variant of γλεῦκος, gleucos, i.e. "sweet new wine, must, sweetness" and from ἁλιεύς, haliéus, i.e. "sailor, seaman, fisher". His wife Pyrrha's name derives from the adjective πυρρός, -ά, -όν, pyrrhós, -á, -ón, i.e. "flame-colored, orange".

Of Deucalion's birth, the Argonautica (3rd century BC) places him in Thessalian Haemonia: "There is a land encircled by lofty mountains, rich in sheep and in pasture, where Prometheus, son of Iapetus, begat goodly Deucalion, who first founded cities and reared temples to the immortal gods, and first ruled over men." According to the Bibliotheca, Deucalion and Pyrrha had at least two children, Hellen and Protogenea, and possibly a third, Amphictyon; other accounts add Melanthea (Melantho), mother of Delphus by Poseidon. The Catalogue of Women names daughters Pandora and Thyia and at least one son, Hellen. Their descendants were said to have dwelt and ruled in Thessaly. One source mentions three sons — Orestheus, Marathonios and Pronous (father of Hellen) — and Deucalion is also credited with a son Candybus, eponym of Candyba in Lycia.

The flood in the time of Deucalion was caused by the anger of Zeus, ignited by the hubris of Lycaon and his sons, descendants of Pelasgus. According to this story, King Lycaon of Arcadia had sacrificed a boy to Zeus, who, appalled by this offering, decided to put an end to the "Bronze" Age by unleashing a deluge. During this catastrophic flood, the rivers ran in torrents and the sea flooded the coastal plain, engulfing the foothills with spray, and washing everything clean. Deucalion, with the aid of his father Prometheus, was saved from this deluge by building a chest. Like the biblical Noah and the Mesopotamian counterpart Utnapishtim, he used this device to survive the great flood with his wife, Pyrrha. The most complete accounts are given by Ovid, in his Metamorphoses (late 1 BCE to early 1 CE), and by the mythographer Apollodorus (1st or 2nd century CE). Deucalion, who reigned over the region of Phthia, had been forewarned of the flood by his father Prometheus. Deucalion was to build a chest and provision it carefully (no animals are rescued in this version of the flood myth), so that when the waters receded after nine days, he and his wife Pyrrha, daughter of Epimetheus, were the one surviving pair of humans. Their chest touched solid ground on Mount Parnassus, or Mount Etna in Sicily, or Mount Athos in Chalkidiki, or Mount Othrys in Thessaly. Hyginus mentioned the opinion of a Hegesianax that Deucalion is to be identified with Aquarius, "because during his reign such quantities of water poured from the sky that the great Flood resulted." Once the deluge was over and the couple had given thanks to Zeus, Deucalion (said in several of the sources to have been aged 82 at the time) consulted an oracle of Themis about how to repopulate the earth. He was told to "cover your head and throw the bones of your mother behind your shoulder". Deucalion and Pyrrha understood that "mother" was Gaia, the mother of all living things, and the "bones" to be rocks. They threw the rocks behind their shoulders and the stones formed people. Pyrrha's became women; Deucalion's became men. These people were later called the Leleges who populated Locris. This can be related to Pindar's account that recounted "Pyrrha and Deucalion came down from Parnassus and made their first home, and without the marriage-bed they founded a unified race of stone offspring, and the stones gave the people their name."

On the other hand, Dionysius of Halicarnassus stated Deucalion's parents to be Prometheus and Clymene, daughter of Oceanus, and mentioned nothing about a flood but instead named him as commander of those from Parnassus who drove the "sixth generation" of Pelasgians from Thessaly.

This atlas entry (deucalion) is the flood-survivor son of Prometheus. Distinct Cretan and Trojan figures also named Deucalion appear under deucalion-crete and related Trojan ids.