According to Genesis, Noah’s Ark was sealed with pitch. Genesis 6:14 instructs Noah to cover the Ark with pitch inside and outside.
Pitch is a thick, waterproofing substance produced from natural materials such as wood or petroleum, depending on the historical setting. In the biblical account, it serves as a practical coating for the vessel’s wooden structure.
The Hebrew term translated as pitch is related to the idea of covering or coating. English translations vary slightly in wording, but “pitch” is the standard traditional answer.
The passage does not specify the exact source or chemical composition of the pitch. It also does not say that the Ark was sealed with tar in the modern industrial sense, although tar is sometimes used as a broad comparison.