what is the importance of Utanapishtim in the epic

Utnapishtim is instructed by Ea to build a boat before the flood that destroyed the city of Shurrupak. Utnapishtim is granted immortality for his role. Gilgamesh seeks him out after Enkidu's death. Utnapishtim tells Gilgamesh of the flood and tells him where to find a magic plant that can grant immortality.