Genesis says Noah coated Noah’s Ark with pitch to make it waterproof.
Genesis 6:14 instructs Noah to cover the ark inside and outside with pitch. The substance is understood as a waterproofing material, although the precise identity of the ancient term is not completely certain. Translations may use words such as pitch, bitumen, or tar.
Pitch and bitumen were familiar waterproofing substances in the ancient Near East. Bitumen, a naturally occurring petroleum-based material, was used in construction and boatbuilding in Mesopotamia. The biblical instruction therefore fits a known ancient technology rather than describing a modern sealant.
The phrase “inside and outside” is significant because it presents waterproofing as part of the ark’s construction, not as a later repair. Genesis also specifies gopher wood, but the exact meaning of “gopher wood” is uncertain. Pitch, by contrast, is identified by its function as the coating that seals the vessel.