diff --git a/VoxelEngine.Tests/WorldGen/CaveCarverTests.cs b/VoxelEngine.Tests/WorldGen/CaveCarverTests.cs
new file mode 100644
index 0000000..e76b893
--- /dev/null
+++ b/VoxelEngine.Tests/WorldGen/CaveCarverTests.cs
@@ -0,0 +1,38 @@
+using OpenTK.Mathematics;
+using VoxelEngine.Core;
+using VoxelEngine.World.Blocks;
+using VoxelEngine.World.Chunk;
+using VoxelEngine.World.WorldGen;
+using Xunit;
+
+namespace VoxelEngine.Tests.WorldGen;
+
+public class CaveCarverTests
+{
+    private static readonly BlockRegistry Blocks = new();
+    private static readonly Configuration Cfg = new();
+
+    private static Chunk MakeStoneChunk()
+    {
+        Chunk c = new();
+        for (int x = 0; x < Chunk.Size; x++)
+        for (int y = 0; y < Chunk.Size; y++)
+        for (int z = 0; z < Chunk.Size; z++)
+            c[x, y, z] = Blocks.Stone.Id;
+        return c;
+    }
+
+    [Fact]
+    public void Carve_IsNoOpOnAirChunk()
+    {
+        var carver = new CaveCarver(seed: 42, Blocks, Cfg);
+        Chunk c = new(); // all-air by default
+
+        carver.Carve(c, new Vector3i(0, 4, 0));
+
+        for (int x = 0; x < Chunk.Size; x++)
+        for (int y = 0; y < Chunk.Size; y++)
+        for (int z = 0; z < Chunk.Size; z++)
+            Assert.Equal(Blocks.Air.Id, c[x, y, z]);
+    }
+}
diff --git a/World/WorldGen/CaveCarver.cs b/World/WorldGen/CaveCarver.cs
new file mode 100644
index 0000000..04c8426
--- /dev/null
+++ b/World/WorldGen/CaveCarver.cs
@@ -0,0 +1,33 @@
+using OpenTK.Mathematics;
+using VoxelEngine.Core;
+using VoxelEngine.World.Blocks;
+using VoxelChunk = VoxelEngine.World.Chunk.Chunk;
+
+namespace VoxelEngine.World.WorldGen;
+
+// Carves caves into an already-terrain-filled chunk. Stateless after
+// construction; the carve methods are pure functions of (chunk, chunkPos).
+// Safe to share across worker threads.
+public sealed class CaveCarver
+{
+    private readonly int _seed;
+    private readonly BlockRegistry _blocks;
+    private readonly Configuration _cfg;
+    private readonly FastNoiseLite _caveNoise;
+
+    public CaveCarver(int seed, BlockRegistry blocks, Configuration cfg)
+    {
+        this._seed = seed;
+        this._blocks = blocks;
+        this._cfg = cfg;
+
+        this._caveNoise = new FastNoiseLite(seed + 100);
+        this._caveNoise.SetNoiseType(FastNoiseLite.NoiseType.OpenSimplex2);
+        this._caveNoise.SetFrequency(cfg.CaveNoiseFrequency);
+    }
+
+    public void Carve(VoxelChunk chunk, Vector3i chunkPos)
+    {
+        // Implemented in Tasks 5 and 6.
+    }
+}