Flood Myths: Sumeria vs. Ireland

The Irish flood story is similar, yet different to the Flood talked about in the Epic of Gilgamesh. In both the flood stories of the Epic of Gilgamesh and the Irish, a flood wipes out the majority of humanity. In the story of Uta-napishti, he was the lone survivor and he was the only person warned about the flood by the gods. The flood lasted 6 days and 6 nights. In the story of the Irish flood, the "higher power" warned Cessair, a woman, to tell her village to escape to the western edge of the world, 40 days before the flood. In the Irish story, three men and three women survived the trip to the edge of the Western world. Each woman was given a male partner. Sadly two of those men died before the flood occurred and there was only one male survivor, Fintan. For being the only survivor, he becomes a salmon and later an eagle and a hawk, living for 5,500 years after the Flood, whence he becomes a man again and recounts Ireland's history. In the Epic of Gilgamesh Uta-napishti was the only survivor of the flood and of the Gods punished him with immortality. The stories are similar because they both tell of a flood that almost wiped out the human race but chose one lone survivor to keep humanity thriving.

Source
http://ireland-calling.com/celtic-mythology-book-of-invasions-cessair-partholon-nemed-fir-bolg/