Each Sinkhole leads to a new Cave or Ruin. When first discovered, the Sinkhole will be a Plugged Sinkhole and is covered with a jagged rubble mound, the player can usually tell they are close to a Plugged Sinkhole on the surface when they find Rocks lying about in the Biomes for no reason. Mining the Plug reveals the hole with a rope going down into its depths while providing Flint and Rocks on the surface and Thulecite and Thulecite Fragments underground. It takes six hits from a Pickaxe to unplug it. Once unplugged, Batilisks will spawn from the Sinkhole at dusk and return underground in the morning.
There are only three Sinkholes in a surface world and one for each Cave. Plugged and open Sinkholes are marked on a map by a gray mound and a hole with a red arrow pointing downwards, respectively.
On default settings, the three surface Sinkholes are guaranteed to spawn in the following locations:
- A Mosaic biome
- A Pig Village (generally, this village also has a Pig King)
- The Forest biome found in the center of the world's Marsh
The number of sinkholes in the world settings can only be "Default" and "None".
Thulecite Sinkholes are usually found in Stalagmite Biomes.
- The sinkholes were plugged up by Maxwell a long time ago, as revealed upon his examination quote.
- Basalt found in previously generated worlds were actually placeholders for Sinkholes and were turned into Sinkholes when the Caves update was released.
- Using DebugSpawn ("basalt") will still spawn Basalt, which doesn't change into a Sinkhole, compared to DebugSpawn("cave_entrance"), which directly spawns a Sinkhole.
- Sinkholes originally had a lighter gray color.
- As of v166227 of DST players are able to create their own dedicated, multi-layer server along with open sinkholes becoming available. These sinkholes, however, have a staircase going down rather than a rope.
- Due to bad world generation sometimes there are no Sinkholes in a Cave.