In Genesis, pitch coated Noah’s Ark to make it watertight.
Genesis 6:14 instructs Noah to cover the ark with pitch inside and outside. The Hebrew wording is related to a term for covering or bitumen, and English translations commonly use “pitch.” In practical terms, the substance functions as waterproofing for the wooden vessel.
The verse does not identify a modern commercial product or specify the exact chemical composition of the material. Ancient peoples used naturally occurring bitumen and related waterproofing substances in construction, boats, and containers, so pitch is a historically plausible description of the text’s coating.
Pitch is not the ark’s building material: Genesis names gopher wood for the structure and pitch for its protective coating. It is also not the same as the rainbow covenant that appears after the flood. Those are separate details in the narrative and answer different questions.