# Why is there a cave every few blocks now? You asked, so we rebuilt both kinds of caves.

- Series: [How It Spawns](https://miu.fm/howitspawns.md)
- Published: 2026-11-01
- Page: https://miu.fm/howitspawns/why-is-there-a-cave-every-few-blocks-now-you-asked-so-we

## Story

Why is there a cave every few blocks now? You asked, so we rebuilt both kinds of caves.

Before 1.18, caves were dug. In Minecraft Beta 1.7.3 (2011) each chunk rolled once, and one in fifteen started caves. By 1.17 the chance was one in seven (probability 0.14285715 in the game's files). A hit sent out diggers, the game's cave carvers: each walks a block a step, swerving and carving, and stops after 85 to 112 steps. Most chunks missed.

In 1.18 (2021) the old diggers still roll: 0.15, plus a new deep one at 0.07. But the underground got twice as deep, down to y -64, and in our rebuild the diggers alone hollow out less than before: about 3 blocks in 100, against about 4 in 100 with 1.17's rules. The new caves aren't rolled at all. Every block underground also gets a number from the cave noise, worked out the same way everywhere, and wherever that number dips below zero, the block is air. In our rebuild that makes about 12 blocks in 100 hollow, more than twice the old. Henrik Kniberg, who worked on Minecraft's world generation, on the new tunnels: "these tunnels can get very long". And Mojang's 1.18 notes: "The old cave carvers and canyons still generate".

The world in this film is our own simplified version, built in code block by block: the carvers' rolls and walk from the game's own code, the 1.18 cave formulas and constants from the game's files, our own random numbers. The shares come from our run of 16 worlds, 256 by 256 blocks each, deep underground; they are not measured in the game.

Old caves had to be started. New caves are already there. Which kind do you like exploring more?

Sources: Minecraft Java Edition Beta 1.7.3 game code (MapGenCaves, two decompiles). Minecraft Java Edition 1.17.1 and 1.18 game code (CaveWorldCarver) and worldgen data (1.16.2 to 1.18.2). Mojang, Minecraft Java Edition 1.18 release notes (November 30, 2021) and Snapshot 21w06a (February 10, 2021). Henrik Kniberg, "Minecraft terrain generation in a nutshell" (video, February 6, 2022).
Not an official Minecraft video. Not approved by or associated with Mojang or Microsoft.

## Watch

- Instagram: https://www.instagram.com/reel/DfNjPxvjx6H/

---

Under copyright law, a quotation must name its source: Miuradio, https://miu.fm/howitspawns/why-is-there-a-cave-every-few-blocks-now-you-asked-so-we

© 2026 Miuradio, https://miuradio.com