Genesis says Noah coated the inside and outside of the Ark with pitch.
Genesis 6:14 instructs Noah to cover the ark with pitch inside and outside. Pitch is a thick, water-resistant substance historically made from tar, bitumen, or related resinous materials. Applying it would seal gaps in wooden construction and help keep water from entering.
The Hebrew wording is related to the idea of covering or atonement, and translators generally render the material as “pitch.” The text does not identify a particular chemical recipe or specify whether the substance was mineral bitumen, plant-derived tar, or another waterproofing compound.
Pitch is part of the Ark's construction instructions, not an animal or a type of wood. The passage separately names gopher wood as the building material. This distinction explains why answers such as cedar or oil do not match the wording of Genesis.