Minecraft wiki entry for Gathering_resources_on_peaceful_difficulty, associated text: Gunpowder, can be found in desert temple chests, dungeon chests, woodland mansion chests and shipwreck chests. See the previous section, "Bones," for how to find these structures. Gunpowder can be found in shipwrecks which can generate in any ocean biome, but rarely you can also find one on land.