In the Genesis account of Noah's Ark, bitumen was used to make the vessel watertight.
Genesis 6:14 instructs Noah to cover the ark inside and outside with a substance translated in many English versions as pitch. The Hebrew term is commonly associated with bitumen, a naturally occurring petroleum-based material used historically for waterproofing and construction. Some translations retain the more general word “pitch,” so the exact English label can vary while the function remains the same.
Bitumen is not the ark's building material; Genesis separately tells Noah to make the vessel from gopher wood, a term whose precise meaning is uncertain. This distinction is easy to miss because both instructions occur in the same verse. The waterproof coating would have sealed seams and protected the wooden structure from water. The passage does not identify a modern recipe, quantity, or application method, and it should not be confused with tar-based products used in later shipbuilding traditions.