Start a CaveBlock Minecraft server

CaveBlock flips the skyblock idea. Instead of an island in the sky, every player starts in solid rock underground and digs, mines and builds outward from there. It is an addon to BentoBox, so it needs BentoBox on a Paper server, and it keeps the usual island features such as teams and protection. This guide installs both and covers the world settings that cannot be changed later.

Checked against CaveBlock 1.23.2 and BentoBox 3.23.4 on Paper 26.2, October 2026. CaveBlock 1.23.2 loads on Paper 26.2 with BentoBox 3.23.4 and Java 25, even though its release notes name Minecraft 1.21.x and Java 21 and the 1.21.0 notes name Paper 1.21.5 to 26.2. PaperMC lists 26.2 as supported but lists 26.1.2 as unsupported (support ended on 26 July 2026), which is why this guide uses 26.2, the newest version in the author's 1.21.0 range.

What you need

• Paper on 26.2. BentoBox 3.23.4 needs Java 25, and the panel runs Java 25 only on 26.x versions. In JAR Manager (under More in the left rail) pick Paper and Minecraft 26.2, then press Apply change (Change your Minecraft version or mod loader). In the window that opens, leave Take a backup first ticked and press and hold Confirm & reinstall for about 3 seconds. Check that the version has changed before you go on, and apply the change again if it has not.
• BentoBox, from the Plugins tab.
• The CaveBlock jar. The newest build is on the project's GitHub releases page. Its Modrinth page only has an older build, 1.20.1, which lists Minecraft up to 1.21.8. Download the jar to your computer.

Install BentoBox and CaveBlock

1. Open Plugins, leave Modrinth selected, search BentoBox and press Install.
2. Open the Console tab, press Start, accept the EULA if asked, and press Stop once the server is up. This creates BentoBox's folders.
3. Open File Manager and go into plugins, BentoBox, then addons.
4. Press Upload in the toolbar, or Upload files if the folder is empty, and choose CaveBlock-1.23.2.jar.
5. Start the server. CaveBlock creates its worlds and a data folder at plugins/BentoBox/addons/CaveBlock with a config.yml.
6. Run bentobox version in the console. CaveBlock should be listed.

Settings to decide before players arrive

Stop the server, then open plugins/BentoBox/addons/CaveBlock/config.yml. If you change anything that affects the worlds, delete the worlds that CaveBlock made, which are named from world-name, caveblock-world by default.

• distance-between-caves is 1000. It cannot be changed once the game is running, and the plugin will not start if it differs from the saved one.
• difficulty is HARD.
• overworld-carvers is true and adds vanilla ravines and wide tunnels. BentoBox does not support changing it mid-game.
• overworld-cave-fill is 0.0. Values from 0.4 to 0.6 thin out the cave network, and 1.0 fills nearly all of it. The config file says it only affects chunks generated after the change.
• structures lets you switch vanilla structures on or off by key. Ancient cities, trial chambers and mansions are off by default, and mineshafts and strongholds are on.

Since 1.21.0 the overworld is carved by Minecraft's own noise generator, so players find real caves, ores and underground biomes under a sealed roof.

Playing

Players run /cave, or /cb. The first call creates their cave and later calls take them home. Admins run /cba or /cbadmin. Make yourself an operator under Players with Make operator to test. The permission prefix for CaveBlock is caveblock, for example caveblock.island.create.

The SKY_WALKER_FLAG world setting controls whether players may walk on the cave roof. For team and challenge features, add BentoBox's other addons the same way, by uploading each jar into plugins/BentoBox/addons.

If something does not work

• CaveBlock is missing from bentobox version. The jar is in the wrong folder, or it was uploaded before BentoBox had made its folders.
• The server stops with an island distance error. distance-between-caves no longer matches the saved caves. Reset the worlds and BentoBox database, or put the value back.
• The console reports an error when a player runs a command. Check the BentoBox and Minecraft versions match, as the BentoBox FAQ says a mismatch causes most of these.