In Genesis, Noah was told to coat the Ark with pitch.
Genesis 6:14 instructs Noah to make the Ark from wood and to cover it with pitch inside and outside. Pitch is a waterproofing substance derived from tar-like organic materials, and its use in the story gives the vessel protection against water entering through seams and joints.
The Hebrew wording is related to the idea of covering or atonement, and translations commonly render the material as pitch, bitumen, or tar. These terms can overlap in ancient contexts, so English versions may differ slightly while referring to a waterproof sealant.
Pitch is separate from the wood used to construct the Ark. Genesis names the wood as gopher wood and separately describes the coating. The passage also mentions the Ark’s dimensions, opening, decks, and side door, making the coating one part of a larger construction description.