In Genesis, Noah was told to use pitch to seal the ark against water.
The instruction appears in Genesis 6:14, where Noah is told to build the ark from gopher wood and coat it with pitch inside and out. Pitch is a waterproofing substance, traditionally associated with bitumen or another tar-like material. Its practical purpose in the narrative is to make the vessel watertight.
Translations vary in how they render some construction terms, especially “gopher wood,” whose exact identity is unknown. The word for pitch is more consistent in meaning, although translations may use terms such as bitumen or tar. The text therefore gives a waterproofing material but does not identify a modern chemical formula or a specific tree species for the wood.