Noah’s ark was sealed with pitch on both the inside and outside.
Genesis 6:14 instructs Noah to cover the ark with pitch, specifying the inside and the outside. Pitch is a tar-like waterproofing substance that could be applied to seams and surfaces, helping keep water from entering a wooden vessel.
The biblical text uses the Hebrew word kopher, related to a word for covering or atonement, and translations commonly render it as pitch. This waterproofing detail is separate from the ark’s construction material, which Genesis calls gopher wood. The text does not provide a modern chemical formula or identify a precise geological source for the pitch.