According to Genesis, pitch coated Noah's Ark on the inside and outside.
Genesis 6:14 instructs Noah to make the ark from gopher wood and to cover it with pitch, or bitumen, inside and out. Pitch is a waterproofing substance made from tar-like materials, so the instruction addresses the vessel's ability to keep water from entering through its wooden structure.
The Hebrew term translated as “pitch” is related to a word for covering or atonement, and translations differ slightly in how they render the construction material. Some versions use “bitumen,” while others retain “pitch.” These wording differences refer to the same general waterproofing idea rather than to a separate decorative coating.
Genesis does not identify “gopher wood” with a known modern tree species. The text gives the wood and the waterproofing material as separate details. Thus, pitch is the specific answer to the coating question, while gopher wood is the stated building material.