How to Build an Underground Base

Common mistakes and fixes

The fastest way to ruin an underground base is one dark corner. Mobs spawn on any floor block at light level 0, so check every block, not just the open middle of a room. Lanterns light 15, torches light 14, both clear a wide circle, but a recessed alcove or a step behind a pillar can still sit dark. Press F3 on Java to read the block light value under your crosshair, or hold a light block while you sweep the floor.

Seal cave openings the moment you hit one. A single hole into a large unlit cave keeps feeding mobs no matter how bright your rooms are. Wall it with any solid block, then break through later on purpose if you want a mine.

Keep ceilings 3 high in main rooms and 2 in side passages. A 2 high room reads as a tunnel, and you cannot place a hanging lantern without an extra block. Carry a water bucket at all times. It cancels fall damage in the shaft, turns lava into stone, and a placed source lets you swim back up if you dig too deep.

• Place a bed underground and sleep in it so a death sends you back inside, not to a random surface spawn. Save respawn anchors for a Nether base, they explode if you use them in the Overworld.
• Beds explode if you sleep in the Nether or the End. Underground in the Overworld they are safe to use.
• Label chests or use a sign wall. In a windowless base you lose track of storage fast.

Blocks and items in this guide

Water BucketCobblestoneSea LanternShroomlightDeepslateGlowstoneObsidianDiamond

All 8 of these are named in the guide above, starting with Water Bucket. Look them up in the item database.