In Genesis, pitch was used to seal Noah’s Ark against water.
Genesis 6:14 tells Noah to cover the Ark with pitch inside and outside. The instruction is a practical part of the construction description: the vessel is made from wood and then treated with a waterproofing substance.
English translations differ in wording. Some use “pitch,” while others use terms such as “bitumen” or “tar,” reflecting the ancient waterproofing material implied by the Hebrew text. For a short canonical answer, “pitch” is the traditional English term.
Pitch is not the Ark’s building material. Genesis separately identifies the wood as gopher wood, while pitch is the coating applied to make the structure watertight.