I have heard many, many conflicting reports on whether or not Crimson will spread in my Ice Biome.

Some people say yes it will, others say that no, it only starts during Hardmode. Still others say it becomes a special kind of biome when it spreads through during Hardmode.

My current base of operations is right next to a snow biome, and I've been thinking of moving it to there to clear out an area for my Arena, but there's a Crimson biome right on the other side of that Ice Biome, and if it's going to spread, I want to be sure my base is safe.

So, does it spread? Does it not? Does it only do it during Hardmode?


Corruption, Hallow, and Crimson can all spread relatively slowly through ice blocks, but not snow blocks.

  • Do you have a source?
    – Zibbobz
    Oct 12 '13 at 11:59
  • From The Crimson page of the wiki: "Sand within Crimson becomes Crimsand. Ice Blocks become Red Ice Blocks." Nov 5 '14 at 15:49

Crimson can spread to ice but not to snow, this makes it one of the easier biomes to keep pure since the crimson spreads slowly through ice and not at all through snow. If you are worried just dig a tunnle dividing the two biomes.

  • I know this answer is several years old, but I am curious - how deep does a tunnel need to be to prevent corruption spread?
    – Zibbobz
    Jun 22 '20 at 12:40

From my experience of playing terraria I have had an annoying corruption trying to take over my world. It has actually taken over the ice biome but from research from the terraria wiki say it only happens in hardmode. If you want to keep your base safe you can just make a 3 wide hole from the surface to the underworld. All of this goes for the corruption, crimson, and hallowed. It works from experimentation and research.

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