Question: why was utnapishtim granted eternal life?
Answer: Exchanging his kingly garments for animal skins as a way of mourning Enkidu, he sets off into the wilderness, determined to find Utnapishtim, the Mesopotamian Noah. After the flood, the gods had granted Utnapishtim eternal life, and Gilgamesh hopes that Utnapishtim can tell him how he might avoid death too.