Valheim Iron Ore is needed to craft iron tools, but iron can be difficult to find. As one of the game's strongest materials, you'll want to know the best places to find Iron Ore.
Valheim Iron Ore: Where to Find
Scrap Iron can be found only in the Sunken Crypt in the Swamp. You'll be looking for Muddy Scrap Piles, which will often be the obstruction to doorways in the dungeon. You need at least an Antler Pickaxe to mine it. In addition to Scrap Iron, you may find Leather Scraps and Withered Bones from Muddy Scrap Piles.
The other way to find Scrap Iron is to loot them from chests within the Sunken Crypt.
Bonemass, the boss of the Sunken Crypt, drops the Wishbone, drops a helpful item for finding more Scrap Iron. The Wishbone can be equipped to track secret items. Hidden Muddy Scrap Piles can be discovered with the Wishbone, which can then be mined for Scrap Iron the same way you did in the dungeon.
To get the Scrap Iron into a usable state, take them to the Smelter. You'll need two Coal to smelt one Iron bar. From here, you can craft them into a variety of items like Iron Armor and weapons.