Alex's Caves | Rare Cave Biomes Mod

Alex's Caves is a Forge mod for Minecraft that adds six rare cave biomes to the Overworld, each with its own mobs, blocks, ambient fog, and mechanics. The biomes are deliberately hard to find, so reaching one feels like an actual discovery rather than another generic tunnel. Built by the team behind Alex's Mobs, the mod leans into atmosphere, lighting, and sound to make every underground area feel distinct. It also ships with built-in compatibility for Just Enough Items and Alex's Mobs.

Finding Your First Underground Cabin

You do not stumble on the new cave biomes by accident. Your starting point is an Underground Cabin, a small structure that can generate in most Overworld biomes. Inside you will find loot barrels containing Cave Tablets and a copy of the Cave Compendium, the in-game guide that walks you through everything the mod adds.

Cabin hunting can be slow. Two shortcuts help. Abandoned mineshafts sometimes hold a map that points to a cabin, and Cartographer villagers will occasionally trade an Underground Cabin Locator map.

The cabin also holds a Spelunkery Table. This is the workbench you use to translate the five Cave Tablets into Cave Codices, one for each cave type. There are five tablets in total, each leading to a different biome.

Translating Tablets at the Spelunkery Table

To translate a tablet, place it on the Spelunkery Table along with a piece of paper, then guess a hidden word using on-screen clues.

Pick a hidden word at random and read it through the magnifying glass. A good guess reveals several letters at once, which narrows the puzzle down. In a lucky run you might expose two adjacent letters that belong to your target word, making the rest obvious.

Match the revealed symbols to the glyphs on the tablet, working out the word letter by letter.

You get five guesses per level and must clear three levels to produce a single codex. Fail a level or interrupt the translation and the tablet is consumed, so it pays to read the clues carefully.

Reading and Using a Cave Codex

A finished Cave Codex does two jobs. Hold it in your main hand and left-click to unlock new entries in the Cave Compendium across four chapters, General, Resources, Inhabitants, and Utilities. Once all four chapters are complete for that biome, the codex stops adding new pages.

The codex also crafts into a Cave Biome Map.

Tracking Down a Biome with Cave Maps

A Cave Biome Map points you toward the nearest biome of the matching type.

Because these biomes are rare, the map takes time to populate and shows an ellipsis texture while it searches. If no biome exists within range, the map warns you and you keep exploring until it locks on.

Once loaded, the map shows your rotation relative to the target and guides you in. The walk can be long and dangerous, but the loot and encounters at the end justify the trip.

Exploring the Six Cave Biomes

With a map in hand you are ready to descend. The mod author recommends turning shaders off, because several biomes rely on custom lighting and fog that shaders can flatten or distort. This overview stays light on spoilers so the discovery stays yours.

Magnetic Caves

Dim and humming with latent energy, the Magnetic Caves are lined with glowing neodymium crystals. Strange entities move through the shadows, and the terrain itself feels alive.

Primordial Caves

Time feels frozen in the Primordial Caves. Ambersol clusters throw an amber glow across wide chambers choked with ancient life, and a pale yellow fog hangs over everything.

Toxic Caves

The Toxic Caves feel diseased. Darkness and low rumbling fill the air, and the whole biome reads as something that should not be touched.

Abyssal Chasm

Hidden beneath the oceans, the Abyssal Chasm is a flooded ruin. Tube Worms sway in the current and the Deep Ones hold court over whatever sank here.

Forlorn Hollows

The Forlorn Hollows are steeped in malice. You cross terrain of Guanostone while Underzealots watch from the dark, looking for sacrifices.

A sixth biome, the Candy Cavity, was added in a later update. You can read the full breakdown of that addition and the Eruption update in our dedicated Alex's Caves Candy Cavity update and Alex's Caves Eruption update posts.

Installing Alex's Caves

This is a Forge mod, so you need a matching Forge installation before the jar will load.

1. Install Minecraft Forge for your game version, then launch the Forge profile once to generate its folders.
2. Download the Alex's Caves jar and the Citadel jar. Citadel is a required library mod that Alex's Caves depends on, and the game will crash without it.
3. Drop both jars into the mods folder inside your Minecraft directory.
4. Launch the Forge profile and start a world. Underground Cabins will begin generating in the Overworld.

If you are new to modded Minecraft generally, our how to install Minecraft mods guide covers the folder structure, profile setup, and common pitfalls.

Frequently Asked Questions

Do I need Alex's Mobs installed too?

No. Alex's Caves runs on its own. The mod does have built-in compatibility with Alex's Mobs, so the two pair well if you want to run them together, but Alex's Mobs is not required.

What is Citadel, and is it really required?

Yes. Citadel is a library mod that several of Alex's projects share, and Alex's Caves will not load without it. Keep the Citadel jar in your mods folder next to the Alex's Caves jar.

Should I play with shaders on?

The mod author recommends playing without shaders. Several biomes use custom lighting, fog, and particle effects that shaders can override or wash out. For the intended look, leave shaders off during your first trip through each biome.

Does it work with Just Enough Items?

Yes. Built-in JEI integration is included, so recipes and item information from the mod show up in the JEI overlay as expected.

Is the project still getting updates?

The most recent release is version 2.0.2 from October 2024. The project has been quiet since then, so check the project page for the current status before building a long-term world around it.

Where to Learn More

The mod ships with detailed documentation covering every biome, mob, item, and mechanic, plus a getting-started guide that expands on everything above.

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