In Genesis, Noah’s Ark was coated with pitch to make it watertight.
The instruction appears in Genesis 6:14, where Noah is told to build the Ark from gopher wood and coat it inside and outside with pitch. Pitch is a waterproofing substance associated with bitumen or tar-like material, although translations differ in how they render the underlying Hebrew word.
This instruction describes sealing the vessel, not its structural material. That distinction matters because “pitch” and “gopher wood” answer two different questions in the same verse. The passage also specifies that the coating should be applied on both the interior and exterior surfaces.
Ancient boats in the Near East commonly used waterproofing substances, including bitumen-based materials. However, the Genesis account does not provide a recipe, quantity, or archaeological evidence linking a surviving vessel to Noah’s Ark.