Table 11 is especially interesting. First, the immortality is possible if Gilgamesh can stay awake and never fall asleep–a rather direct metaphor.  Then…

Utanapishtim spoke to Gilgamesh, saying:
“Gilgamesh, you came here exhausted and worn out.
What can I give you so you can return to your land?
I will disclose to you a thing that is hidden, Gilgamesh,
a… I will tell you.
There is a plant… like a boxthorn,
whose thorns will prick your hand like a rose.
If your hands reach that plant you will become a young
man again.”
Hearing this, Gilgamesh opened a conduit(!) (to the Apsu)
and attached heavy stones to his feet.
They dragged him down, to the Apsu they pulled him.
He took the plant, though it pricked his hand,
and cut the heavy stones from his feet,
letting the waves(?) throw him onto its shores.
Gilgamesh spoke to Urshanabi, the ferryman, saying:
“Urshanabi, this plant is a plant against decay(!)
by which a man can attain his survival(!).
I will bring it to Uruk-Haven,
and have an old man eat the plant to test it.
The plant’s name is ‘The Old Man Becomes a Young Man.'”
Then I will eat it and return to the condition of my youth.”
At twenty leagues they broke for some food,
at thirty leagues they stopped for the night.
Seeing a spring and how cool its waters were,
Gilgamesh went down and was bathing in the water.
A snake smelled the fragrance of the plant,
silently came up and carried off the plant.

So a serpent takes away access to the tree of life?

There is also a line or two about trading animal skins for royal robes, but I may be getting overly suggestive.