Biomes
Biomes define climate, visuals, mob spawns, carvers, and the placed features list for each decoration step. In Minecraft, biomes control not just the terrain appearance but also weather behavior, mob spawning rules, and which features generate.
How Biomes Work
In the Overworld, biome placement is determined by 6 climate parameters:
- Temperature - Controls snow/ice coverage and vegetation types (5 levels from frozen to hot)
- Humidity - Affects vegetation density (5 levels from arid to humid)
- Continentalness - Determines ocean/beach/inland placement
- Erosion - Controls flat vs mountainous terrain (7 levels)
- Weirdness - Triggers biome variants (e.g., Jungle → Bamboo Jungle)
- Depth - Determines surface vs cave biomes
These parameters form a 6D space where each biome occupies defined intervals. The game selects the closest matching biome for any given location.
References: Biome, Biome definition
Basic Biome
Effects
The effects block controls visual and audio aspects of the biome. These settings define the atmosphere players experience, from sky color to ambient sounds.
Reference: Biome definition - Effects
Spawners
Define mob spawn rules per category. Each spawner entry specifies the entity type, spawn weight (relative probability), and count range. Higher weights mean more frequent spawns relative to other entries in the same category.
Reference: Biome definition - Mob spawning
Spawn Costs
Spawn costs control mob density using an energy budget system. Each mob type has an energyBudget (max population density) and charge ( cost per mob). This prevents overcrowding while allowing natural mob distribution.
Reference: Biome definition - Spawn costs
Carvers
Carvers hollow out terrain to create caves and canyons. They run during the carvers generation step, after terrain noise but before features. Two carving modes exist: air for standard caves and liquid for underwater caves.
Reference: Carver
See Carvers below for creating configured carvers.
Features
Features are attached to biomes via decoration steps. Each step runs in order during chunk generation, with structures placing before features within the same step. See the main worldgen page for the full step list.
Reference: Biome definition - Features
See Features for creating configured and placed features.
Carvers (Caves/Canyons)
Configured carvers remove terrain to form cave systems and canyons. They use noise-based algorithms to create natural-looking underground spaces. Carvers run after terrain generation but before features, ensuring caves don't destroy placed decorations.
Minecraft has two carver types:
- Cave carvers - Create winding tunnel systems with variable radius
- Canyon carvers - Create deep ravines with steep walls
References: Carver, Configured carver
