In Genesis, Noah was instructed to put pitch on the Ark to make it waterproof. Genesis 6:14 says he should cover the vessel inside and outside with pitch.
Pitch is a waterproofing substance made from tar-like or resinous material. The biblical instruction reflects a practical boat-building technique: sealants were used to prevent water from entering through joints and gaps. Genesis gives the waterproofing instruction immediately after naming the wood, so the two materials have distinct roles.
The Hebrew word translated “pitch” is related to a root meaning to cover or coat. English versions may use “bitumen,” “tar,” or “pitch,” depending on translation choices. These terms describe the sealing function, not the Ark’s structural material. The passage therefore does not say that the Ark was made of pitch; it says that pitch coated its inside and outside surfaces.