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UnderWorld SMP ModpackMinecraft modpack for 1.21.1

A heavily modded Minecraft experience focused on underground exploration, survival, and community. Dig deep, build creatively, and thrive in a world where the real adventure starts below the surface.

client and servernewest supported release 1.21.1TechnologyAdventureOptimizationCombat
Latest version
1.2.9
Minecraft
1.21.1
Java
Java 21+
Loaders
Fabric, NeoForge
Licence
MIT
Downloads
1.0k
Updated
10 mo ago
Available on
Modrinth
Space NodeOur hosting

Host UnderWorld SMP Modpack servers

One click and UnderWorld SMP Modpack is installed with the right loader, on hardware built for it.

  • 1.21.1
  • Fabric
  • NeoForge
  • One click modpack install
  • Dependencies handled
  • Tuned startup flags
  • NVMe SSD
Deploy a serverFrom €0.90 per GB

Screenshots

Click a screenshot to open it. Screenshots are served from the author’s own host and belong to them.

Minecraft versions

Every version UnderWorld SMP Modpack declares support for, newest first, with the Java runtime that version needs.

Other modpacks
MinecraftThroughJavaEvidenceReleased
1.21.1Fabric, NeoForge21+declared8 Aug 2024

Download

From UnderWorld SMP Modpack’s own host. Nothing is re-hosted here.

For Minecraft 1.21.1

Choose the loader you use before downloading.

  • NeoForge

    1.2.9 · 4 Jan 2026 · UnderWorld SMP v1.2.9.mrpack

    Get NeoForge

  • Fabric

    1.1.0 · 16 Jul 2025 · UnderWorld SMP Modpack 1.1.0.mrpack

    Get Fabric

Most recently published release

1.2.9release4 Jan 2026

UnderWorld SMP v1.2.9.mrpack · 25.4 MB · for 1.21.1 · NeoForge

Download this release
4710172eba7d…
Older versions10
  • 1.3.726 Oct 20251.21.1198.3 MB83 downloadsb3040cf86d88…Get
  • 1.3.41 Oct 20251.21.1209.9 MB75 downloadsb3a6d75cfaeb…Get
  • 1.2.71 Oct 20251.21.116.0 MB28 downloads7e5b3d9c22ea…Get
  • 1.3.38 Sept 20251.21.1208.8 MB68 downloadsd1dd17bd7021…Get
  • 1.3.129 Aug 20251.21.117.1 MB41 downloads254b3b190fc2…Get
  • 1.2.625 Aug 20251.21.115.9 MB21 downloads51aede46dbf4…Get
  • 1.2.524 Aug 20251.21.115.1 MB17 downloads06de3bd17b65…Get
  • 1.2.029 Jul 20251.21.181 KB23 downloads05adf298658c…Get
  • 1.1.016 Jul 20251.21.13.7 MB64 downloads2e0bfb376727…Get
  • 1.0.024 Apr 20251.21.14.8 MB122 downloadsfc6551b6a201…Get

Frequently asked

Does UnderWorld SMP Modpack work on Minecraft 1.21.1?

Yes. 1.21.1 is the newest Minecraft version UnderWorld SMP Modpack declares support for, and the claim comes from the author's own release metadata rather than from a compatibility list somebody maintains by hand.

Do I need to install UnderWorld SMP Modpack on the client or the server?

Both. Every player needs it installed and so does the server, so anyone joining without it will be refused.

Which platform or loader does UnderWorld SMP Modpack support?

Fabric, NeoForge. A build for one platform or loader will not necessarily load on another, so this is the first thing to check before the Minecraft version.

Which Java version do I need for UnderWorld SMP Modpack?

Among the supported Minecraft releases above, the highest recorded requirement is Java 21 or newer. Use the requirement for the exact Minecraft version you run; previews and snapshots may differ.

What licence is UnderWorld SMP Modpack under?

MIT, as stated by the author on the platform we synced it from. Check the project's own page before redistributing or bundling it.

How do I install UnderWorld SMP Modpack?

Use a launcher that imports packs, such as Prism Launcher, the Modrinth App or the CurseForge app, and open the pack file with it. The launcher installs the right loader and mods for you; installing a pack's mods by hand is the error-prone way.

Where do I download UnderWorld SMP Modpack safely?

Start with the author's page on Modrinth, which is where the data here is synced from. MCReference does not host or repackage files. When available, recorded download links go to the source for that release; verify the publisher, filename and any available checksum before running it.

Works on the same versions

Ordered by how much of the recent Minecraft version coverage overlaps, not by popularity.

Re-ConsoleA continued Legacy Console Edition experience, expanded upon with modern Java Edition content and QoL! (An Official Legacy4J Project)MAX FPS: Optimized🚀 MAX FPS WITHOUT UNNECESSARY MODS! Only 16 optimization mods - NOTHING EXTRA! ✅ ALL MAJOR VERSIONS ⚡ INSTALLS ON ANY LAUNCHER! (Guide below)PacktrixPre-packed Official Modpack containing Patrix Resource Pack for easy install using Fabric/Quilt.Simply Optimized ReloadedAn unofficial port of Simply Optimized built to support every major mod loader and stay current with the newest versions of Minecraft.FPS+ PvP Boost | Ultimate FPS & Combat Client [ Every Version ]Ultra-lightweight FPS boost & PvP modpack for Fabric. Boost FPS on low-end PCs with Sodium optimizations, lower input lag, cleaner visuals, and combat HUD tweaks built for Hypixel Bedwars, Duels, PotPvP & CPVP. Maximize frames and dominate fights.香草精华 Vanilla EssenceFaithful to the origional. Better vanilla experience without any new blocks or mobs

Details from Modrinth, where the author last updated it on 4 Jan 2026. We do not host files or republish descriptions. Available download links point to the author’s own release.

Is this information wrong or missing something? .