In Genesis, Noah’s ark was sealed with pitch to make it watertight.
Genesis 6:14 instructs Noah to cover the ark inside and outside with pitch. The Hebrew wording is related to bitumen or a similar waterproofing substance, and English translations commonly use “pitch.”
Pitch is a broad term for a dark, sticky waterproofing material. In the ancient Near East, bituminous substances were used in construction and boat-building, especially in regions where natural bitumen was available.
This detail is separate from the ark’s building material: Genesis identifies gopher wood for the structure and pitch for waterproofing. The passage does not specify a modern chemical formula or one exact mineral source.