Overview
FireHole is a Valheim world location that spawns in the swamp biome, identified internally as FireHole. World generation places up to 200 per world, with terrain constraints (min altitude 0.5), and an exclusion radius of 5.2m, which is why some seeds have far more of them than others.
About
FireHole is a fire geyser found in the Swamp. It continuously spawns Surtlings and yields Coal and Surtling cores when the Surtlings die over water.