According to Genesis, Noah’s Ark was sealed with pitch to keep out water.
Genesis 6:14 tells Noah to make rooms in the ark and cover it inside and outside with pitch. Pitch is a waterproofing substance, generally understood as a tar-like or bituminous material. The instruction addresses the vessel’s watertightness rather than its basic construction material.
This detail is sometimes confused with the wood used to build the ark. Genesis calls for “gopher wood,” a term whose exact botanical meaning remains uncertain. Pitch, by contrast, is the coating applied to the inside and outside surfaces.
Ancient boatbuilders across the Near East used bitumen and related substances to waterproof boats and containers. Archaeological evidence from Mesopotamia shows the practical importance of bitumen in ancient watercraft, although no archaeological vessel has been identified as Noah’s Ark. The biblical passage gives the religious narrative’s construction instruction, not a surviving technical blueprint.