In the Book of Genesis, Noah used pitch to waterproof the Ark.
Genesis 6:14 tells Noah to cover the Ark inside and outside with pitch. The substance is described as a coating intended to make the large wooden vessel watertight. English translations generally retain the short word “pitch,” although the exact ancient material is not identified.
Pitch traditionally refers to a sticky waterproofing substance derived from wood or petroleum-like natural sources. Ancient boatbuilders in the Near East used bitumen and related materials for sealing boats, baskets, and building surfaces, making the biblical instruction plausible as a description of waterproofing practice.
The passage does not specify the recipe, thickness, or source of the pitch. It also does not say that the Ark was coated only on the outside; Genesis explicitly mentions both inside and outside. Thus “pitch” is the precise biblical answer, while bitumen is a possible historical comparison rather than the wording of the verse.