According to Genesis, Noah coated the Ark with pitch to make it watertight.
Genesis 6:14 instructs Noah to cover the vessel with pitch inside and outside. Pitch is a thick, waterproofing substance associated historically with tar, bitumen, resin, or similar materials used to seal wood and boats.
The wording is significant because the Ark is presented as a huge wooden vessel intended to endure prolonged flooding. The passage gives the waterproofing instruction alongside the building material, compartments, decks, and dimensions.
Modern readers sometimes assume that “pitch” identifies one precise chemical product. It does not. Ancient translations and modern versions may use terms such as tar or bitumen, and the original word has been interpreted in more than one way. The biblical text clearly emphasizes waterproof sealing, while the exact substance remains uncertain.