Unstable Underworld
Unstable Underworld, by aspectfromthetap, adds a second dimension reached through a portal built below the Nether, and players who fall into the void can arrive there.
What it does
The mod adds an Underworld dimension under the Nether, reached by building a nether portal in a specific shape. The portal frame takes five obsidian blocks in a height of four, with the bottom made of ore so it stays lit. Players who dig down past the Nether's bedrock layer will not find a floor and fall into the void; instead of dying there, they are sent to the Underworld, which takes fall damage on arrival. The dimension contains five new biomes.
The mod is server required and client optional: the server must run it, and players may join without installing it. The author credits the design to Unstable SMP and notes that the idea comes from videos by the Unstable creators. The mod is published for Fabric, Forge, NeoForge and Quilt, with files for 26.3, and as a data pack, across 12 release versions, covering 1.21.5 – 26.3. The code is not open source, and all rights are reserved.
Key features
Underworld dimension
A dimension below the Nether, with its own terrain and five new biomes for players to explore.
Specific portal shape
The Underworld portal requires five obsidian blocks in a height of four, with ore at the bottom so it works.
Void fall route
Players who fall through the bottom of the Nether's bedrock layer are carried to the Underworld instead of dying.
Fall damage on arrival
Arriving in the Underworld by falling deals fall damage, so the route is not free.
Gallery
Compatibility
Latest build for each game version and loader.
26.x5 of 5 versions with builds
1.21.x7 of 7 versions with builds
Only full game releases are shown. This mod publishes no snapshot builds.
Questions
Does Unstable Underworld need to be installed on the client?
Which loaders does Unstable Underworld support?
In the catalog
Unstable Underworld is one of 7,555 Cursed mods on ModsFinder, and one of 4,235 Cursed mods for Fabric. 8,071 mods support Minecraft 26.3.
More from aspectfromthetap
Similar mods
What the author says
This Datapack adds the unstable inspired Underworld Dimension to minecraft. Below the nether, if you dig, you will not find bedrock. Instead, you will find void, And that void, that void will lead to The Underworld!
Official listing
- Modrinth page
- modrinth.com/mod/unstableunderworld
- Owner
- aspectfromthetap
- Published
- 2026-09-26
- Updated on Modrinth
- 2026-09-26
- Facts verified
- 2026-10-15