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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 1.21.1TechnologyAdventureOptimizationCombat
Latest version
1.2.9
Minecraft
1.21.1
Java
Java 21+
Loaders
Fabric, NeoForge
Licence
MIT
Downloads
1.0k
Updated
8 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.

1.2.9release4 Jan 2026

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

Download latest
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 20251.21.10.1 MB23 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?

On the newest Minecraft version it supports, Java 21 or newer. The requirement comes from the Minecraft version you run rather than from the modpack itself, so on an older supported Minecraft the answer is that version's Java, not this one.

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. The download link goes to the source recorded for that release; verify the publisher, filename and 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.ElixirA well-researched performance & optimization modpack to make the game run smoother! With shader & Fresh Animations support. 26.3 ✔OptimumFuse[1.21.5] [Fabric📜] An open-source modpack that improves the game's performance and visuals, inspired by OptiFine, while staying true to the vanilla Minecraft experience.

Last checked 2 mo ago against Modrinth. We do not host files and we do not republish descriptions; every download link points at the author’s own release.

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