Noah applied pitch inside and outside the Ark to make it watertight.
Genesis 6:14 tells Noah to cover the Ark with pitch inside and outside. The Hebrew wording is related to a root meaning “to cover” or “to atone,” while the substance itself is generally understood as bitumen, tar, or another waterproofing material.
Pitch was a practical choice for sealing gaps in wooden construction. Ancient boatbuilders in the Near East used bituminous substances for waterproofing, especially in regions where naturally occurring asphalt was available. Genesis does not specify the source, recipe, or exact chemical composition of the pitch.
The instruction is separate from the Ark’s wood. “Gopher wood” identifies the construction material, while pitch provides the protective seal. Modern retellings sometimes describe pitch simply as tar, but “pitch” is the traditional English answer and the concise term used in the biblical description.