Where to find Obsidian in Valheim

Obsidian is found in the Mountains of Valheim. It comes from deposits you break with a pickaxe.

Tools that can do it: Iron Pickaxe and Black Metal Pickaxe.

Where the world generator places it

The world is made of zones, 64 m on a side. For each zone the game tries to place the number below, in the biomes listed; where it can land is also limited by altitude and the lie of the ground. A number below 1 is the chance that one is placed in a zone.

Open the seed map to see the biomes of your world, then look in the ones above. See Obsidian for what it makes and the console command to spawn it.