Gilgamesh suddenly realises that the old man is none other than Utanapishtim himself! Seeing that Utanapishtim seems to be an ordinary man, he asks why the gods would have granted him immortality.
By way of an explanation, Utanapishtim proceeds to relate the Story of the Flood:
Utanapishtim once resided in the ancient city of Shuruppak, where the gods still lived among the people. For unknown reasons, the gods determined to destroy the humans with a flood. (Ishtar blamed herself for this, for having said untold “evil things” about the humans in the Council of the Gods.)
But Ea, the “clever prince” of the gods, was friends with Utanapishtim, and warned him of the coming flood by talking aloud about it whilst on the opposite side of a reed wall from where he knew Utanapishtim to be. He instructed Utanapishtim to build a huge boat and take his family and animals inside.
Utanapishtim did so, and they rode out the flood for six days and seven nights, finally landing on the side of Mount Nimush. He then released in sequence three birds, and when the third did not return, he determined it was time to leave the ark. They did so, and sacrificed a sheep to thank the gods for their safe delivery. The gods came down, smelling this, and Belitili (Utanapishtim’s wife) said she would remember this day just like she would always remember her necklace of lapis lazuli.
Enlil then turned up (although informed by Belitili that he was unwelcome) and was mightily pissed off that the humans were still alive, having expected them to be wiped out by the flood. He rightly blamed Ea for orchestrating their survival, but Ea responded indignantly, telling Enlil that the punishment of wiping out the entire race was disproportionate.
Enlil suddenly regretted what they’d done, and to compensate, instructed that Utanapishtim and Belitili would be made immortal.
Utanapishtim concludes the story by asking Gilgamesh under what circumstances will someone convene the gods on his behalf to obtain eternal life.
Gilgamesh acknowledges the singular set of circumstances under which Utanapishtim became immortal, but at the same time believes he has earned something through all his trials to get here, and still enquires as to the odds of him getting what he’s after.
Utanapishtim sets Gilgamesh a challenge: stay awake for a whole week, just like they’d had to on the boat during the flood. If Gilgamesh can do this, Utanapishtim will deliver. (Clearly, though, Utanapishtim has no secret to share and no way to deliver on this promise, he just knows Gilgamesh will fail, and is in the mood to jerk him around.)
Gilgamesh says the challenge is an easy one, sits down to wait out the week, and immediately falls asleep.
Belitili says they should now just wake him up and send him home, but Utanapishtim insists they let him sleep, and instructs Belitili to bake a loaf of bread for each day Gilgamesh sleeps, as evidence, as he believes otherwise Gilgamesh will deny or disbelieve he has been asleep.
Belitili complies, and at the end of a week, as the seventh loaf is baked, Utanapishtim reveals the earlier loaves in their various states of decay, and touches Gilgamesh to wake him up. Gilgamesh believes he has just nodded off, but Utanapishtim shows him the bread. Dejected, Gilgamesh realises he has failed, and makes to leave on the boat with Urshanabi. As they make to leave, Utanapishtim tells Urshanabi not to bother coming back (presumably as punishment for bringing Gilgamesh there).
Just as they’re going, though, Belitili feels sorry for Gilgamesh, and asks her husband if there’s nothing they can do to help him. Utanapishtim responds to her kindness, and tells Gilgamesh of a plant, the Boxthorn, that grows on the bottom of the sea, and while not granting immortality, it does restore a person’s youth.
Gilgamesh is elated at this news, and he and Urshanabi set off to find it. Gilgamesh straps heavy stones to his feet and descends to the bottom of the ocean, retrieving the Boxthorn. He tells Urshanabi his plan, that they will return to Uruk, first allow an old man there to test the plant and make sure it works, and then Gilgamesh himself will have some and become young again.
On the way back to Uruk, they stop at a shady pool to rest and bathe, and while there, a snake swallows the Boxthorn, shedding its skin afterwards as its youth is restored.
Gilgamesh is crushed by the loss of the Boxthorn, wondering aloud to what end he has gone through all these trials. Urshanabi counsels him to get a grip on himself.
Suddenly, at his lowest ebb, Gilgamesh spies in the far-away distance the walls of Uruk-Haven, and has an epiphany that, although he cannot live forever, his walls and his city will live on long after he is gone, and he realises that what he has built with his people is his legacy.
Gilgamesh and Urshanabi return to Uruk-Haven, and Gilgamesh triumphantly exhorts Urshanabi to observe the finely built walls of the city, as the tale of the Epic comes to an end.