In Genesis's Noah's Ark story, pitch was used to waterproof the Ark inside and outside.
Genesis 6:14 tells Noah to cover the Ark with pitch both internally and externally. Pitch is a sticky, waterproofing substance historically associated with tar or bitumen, materials used to seal wooden boats and other structures.
The instruction is a practical construction detail within the story. It explains how the wooden vessel could be made watertight before the Flood. The text does not specify the chemical composition, source, or application method of the pitch.
Pitch is sometimes confused with “gopher wood,” but the two serve different roles in the passage: gopher wood is the stated building material, while pitch is the coating. The Ark’s other construction details include compartments, three levels, a window, and a side door.