In Genesis, Noah waterproofed the Ark with pitch.
Genesis 6:14 instructs Noah to make the ark from gopher wood and to cover it with pitch inside and outside. Pitch is a waterproofing substance traditionally associated with bitumen, tar, or another viscous sealant. Applying it to both surfaces would help prevent water from entering through seams and gaps.
The Hebrew word translated as “pitch” is related to a term for covering or atonement in some interpretations, which has encouraged theological discussion. English Bible translations generally preserve the practical meaning: a coating used to seal the vessel. The passage does not identify the precise chemical composition of Noah’s pitch.
This detail is sometimes confused with the ark’s construction material. Genesis names gopher wood as the building material and pitch as the waterproofing coating. Modern reconstructions often use wood, tar, and other sealants, but no archaeological Ark has been authenticated.