Minecraft wiki entry for Fog, associated text: In prior versions of Java Edition (specifically Beta 1.8 Pre-release through 14w34b inclusive, up to its removal in 14w34c), a thick black fog was introduced. As the player descended below Y=17[verify] in the Overworld, this fog would start to appear. As the player traveled deeper, the fog at the edge of the render distance would become closer until the player reached the first layers of bedrock, where visibility was reduced to just a few blocks, beyond which was complete darkness. The gray void particles appeared below Y=17, as well as in the void.