In the Epic of Gilgamesh, Utnapishtim uses bitumen to seal his boat.
Tablet XI describes the construction of Utnapishtim’s flood vessel and says that he uses bitumen and oil in its preparation and sealing. Bitumen is a naturally occurring petroleum-based material that was widely used in the ancient Near East as a waterproofing substance.
This detail belongs to the Mesopotamian flood tradition, not to the Genesis wording. Genesis says Noah’s Ark was coated with pitch, a related waterproofing concept, but the two passages should not be treated as identical texts or exact translations of one another.
Bitumen was practical for boatbuilding because it could fill gaps and help resist water. The term is therefore both a technical construction detail and a clue to the material culture of ancient Mesopotamia.