diff --git a/src/main/java/ru/betterend/mixin/common/ServerWorldMixin.java b/src/main/java/ru/betterend/mixin/common/ServerWorldMixin.java
index 0aab95ac..a48eca97 100644
--- a/src/main/java/ru/betterend/mixin/common/ServerWorldMixin.java
+++ b/src/main/java/ru/betterend/mixin/common/ServerWorldMixin.java
@@ -2,6 +2,7 @@ package ru.betterend.mixin.common;
 
 import java.io.File;
 import java.util.List;
+import java.util.Locale;
 import java.util.concurrent.Executor;
 
 import org.spongepowered.asm.mixin.Mixin;
@@ -32,21 +33,39 @@ import ru.betterend.world.generator.GeneratorOptions;
 
 @Mixin(ServerWorld.class)
 public class ServerWorldMixin {
+	private static final int DEV_VERSION = be_getVersionInt("63.63.63");
+	private static final int FIX_VERSION = DEV_VERSION;
+	private static String lastWorld = null;
+	
 	@Inject(method = "<init>*", at = @At("TAIL"))
 	private void be_onServerWorldInit(MinecraftServer server, Executor workerExecutor, LevelStorage.Session session, ServerWorldProperties properties, RegistryKey<World> registryKey, DimensionType dimensionType, WorldGenerationProgressListener worldGenerationProgressListener, ChunkGenerator chunkGenerator, boolean debugWorld, long l, List<Spawner> list, boolean bl, CallbackInfo info) {
-		File beData = new File(FabricLoader.getInstance().getGameDir().getParent().toString(), "saves/" + properties.getLevelName() + "/data/betterend_data.nbt");
+		if (lastWorld != null && lastWorld.equals(session.getDirectoryName())) {
+			return;
+		}
+		
+		lastWorld = session.getDirectoryName();
+		
+		@SuppressWarnings("resource")
+		ServerWorld world = (ServerWorld) (Object) this;
+		File dir = session.getWorldDirectory(world.getRegistryKey());
+		if (!new File(dir, "level.dat").exists()) {
+			dir = dir.getParentFile();
+		}
+		File data = new File(dir, "data/betterend_data.nbt");
+		
 		ModMetadata meta = FabricLoader.getInstance().getModContainer(BetterEnd.MOD_ID).get().getMetadata();
-		String version = BetterEnd.isDevEnvironment() ? "development" : meta.getVersion().toString();
+		int version = BetterEnd.isDevEnvironment() ? DEV_VERSION : be_getVersionInt(meta.getVersion().toString());
 		
-		WorldDataUtil.load(beData);
+		WorldDataUtil.load(data);
 		CompoundTag root = WorldDataUtil.getRootTag();
-		String dataVersion = root.getString("version");
+		int dataVersion = be_getVersionInt(root.getString("version"));
 		GeneratorOptions.setPortalPos(NbtHelper.toBlockPos(root.getCompound("portal")));
-		boolean fix = !dataVersion.equals(version);
 		
-		if (fix) {
-			DataFixerUtil.fixData(beData.getParentFile());
-			root.putString("version", version);
+		if (dataVersion < version) {
+			if (version < FIX_VERSION) {
+				DataFixerUtil.fixData(data.getParentFile());
+			}
+			root.putString("version", be_getVersionString(version));
 			WorldDataUtil.saveFile();
 		}
 	}
@@ -60,4 +79,24 @@ public class ServerWorldMixin {
 			}
 		}
 	}
+	
+	private static int be_getVersionInt(String version) {
+		if (version.isEmpty()) {
+			return 0;
+		}
+		try {
+			String[] values = version.split("\\.");
+			return Integer.parseInt(values[0]) << 12 | Integer.parseInt(values[1]) << 6 | Integer.parseInt(values[1]);
+		}
+		catch (Exception e) {
+			return 0;
+		}
+	}
+	
+	private static String be_getVersionString(int version) {
+		int a = (version >> 12) & 63;
+		int b = (version >> 6) & 63;
+		int c = version & 63;
+		return String.format(Locale.ROOT, "%d.%d.%d", a, b, c);
+	}
 }
diff --git a/src/main/java/ru/betterend/registry/EndFeatures.java b/src/main/java/ru/betterend/registry/EndFeatures.java
index ca213e77..5adb90c9 100644
--- a/src/main/java/ru/betterend/registry/EndFeatures.java
+++ b/src/main/java/ru/betterend/registry/EndFeatures.java
@@ -59,6 +59,7 @@ import ru.betterend.world.features.terrain.SulphuricCaveFeature;
 import ru.betterend.world.features.terrain.SulphuricLakeFeature;
 import ru.betterend.world.features.terrain.SurfaceVentFeature;
 import ru.betterend.world.features.terrain.caves.RoundCaveFeature;
+import ru.betterend.world.features.terrain.caves.TunelCaveFeature;
 import ru.betterend.world.features.trees.DragonTreeFeature;
 import ru.betterend.world.features.trees.GiganticAmaranitaFeature;
 import ru.betterend.world.features.trees.HelixTreeFeature;
@@ -198,6 +199,7 @@ public class EndFeatures {
 	public static final EndFeature OBSIDIAN_PILLAR_BASEMENT = EndFeature.makeChansedFeature("obsidian_pillar_basement", new ObsidianPillarBasementFeature(), 8);
 	public static final EndFeature OBSIDIAN_BOULDER = EndFeature.makeChansedFeature("obsidian_boulder", new ObsidianBoulderFeature(), 10);
 	public static final EndFeature FALLEN_PILLAR = EndFeature.makeChansedFeature("fallen_pillar", new FallenPillarFeature(), 20);
+	public static final EndFeature TUNEL_CAVE = EndFeature.makeRawGenFeature("tunel_cave", new TunelCaveFeature(), 2);
 	
 	// Ores //
 	public static final EndFeature THALLASIUM_ORE = EndFeature.makeOreFeature("thallasium_ore", EndBlocks.THALLASIUM.ore, 12, 6, 0, 16, 128);
@@ -254,6 +256,7 @@ public class EndFeatures {
 		
 		if (EndBiomes.getBiome(id).hasCaves()) {
 			addFeature(ROUND_CAVE, features);
+			addFeature(TUNEL_CAVE, features);
 		}
 		
 		EndBiome endBiome = EndBiomes.getBiome(id);
@@ -271,6 +274,7 @@ public class EndFeatures {
 		
 		if (def.hasCaves()) {
 			def.addFeature(ROUND_CAVE);
+			def.addFeature(TUNEL_CAVE);
 		}
 	}
 	
diff --git a/src/main/java/ru/betterend/util/SplineHelper.java b/src/main/java/ru/betterend/util/SplineHelper.java
index b15ac46b..b5e15f59 100644
--- a/src/main/java/ru/betterend/util/SplineHelper.java
+++ b/src/main/java/ru/betterend/util/SplineHelper.java
@@ -33,6 +33,29 @@ public class SplineHelper {
 		return spline;
 	}
 	
+	public static List<Vector3f> smoothSpline(List<Vector3f> spline, int segmentPoints) {
+		List<Vector3f> result = Lists.newArrayList();
+		Vector3f start = spline.get(0);
+		for (int i = 1; i < spline.size(); i++) {
+			Vector3f end = spline.get(i);
+			for (int j = 0; j < segmentPoints; j++) {
+				float delta = (float) j / segmentPoints;
+				delta = 0.5F - 0.5F * MathHelper.cos(delta * 3.14159F);
+				result.add(lerp(start, end, delta));
+			}
+			start = end;
+		}
+		result.add(start);
+		return result;
+	}
+	
+	private static Vector3f lerp(Vector3f start, Vector3f end, float delta) {
+		float x = MathHelper.lerp(delta, start.getX(), end.getX());
+		float y = MathHelper.lerp(delta, start.getY(), end.getY());
+		float z = MathHelper.lerp(delta, start.getZ(), end.getZ());
+		return new Vector3f(x, y, z);
+	}
+	
 	public static void offsetParts(List<Vector3f> spline, Random random, float dx, float dy, float dz) {
 		int count = spline.size();
 		for (int i = 1; i < count; i++) {
diff --git a/src/main/java/ru/betterend/util/WorldDataUtil.java b/src/main/java/ru/betterend/util/WorldDataUtil.java
index cb6b1816..e881ba09 100644
--- a/src/main/java/ru/betterend/util/WorldDataUtil.java
+++ b/src/main/java/ru/betterend/util/WorldDataUtil.java
@@ -15,7 +15,7 @@ public class WorldDataUtil {
 		saveFile = file;
 		if (file.exists()) {
 			try {
-				root = NbtIo.read(file);
+				root = NbtIo.readCompressed(file);
 			}
 			catch (IOException e) {
 				BetterEnd.LOGGER.error("World data loading failed", e);
@@ -48,7 +48,7 @@ public class WorldDataUtil {
 	
 	public static void saveFile() {
 		try {
-			NbtIo.write(root, saveFile);
+			NbtIo.writeCompressed(root, saveFile);
 		}
 		catch (IOException e) {
 			BetterEnd.LOGGER.error("World data saving failed", e);
diff --git a/src/main/java/ru/betterend/util/sdf/SDF.java b/src/main/java/ru/betterend/util/sdf/SDF.java
index c5db2106..74aff385 100644
--- a/src/main/java/ru/betterend/util/sdf/SDF.java
+++ b/src/main/java/ru/betterend/util/sdf/SDF.java
@@ -273,4 +273,38 @@ public abstract class SDF {
 			world.setBlock(info.getPos(), info.getState());
 		});
 	}
+	
+	public Set<BlockPos> getPositions(ServerWorldAccess world, BlockPos start) {
+		Set<BlockPos> blocks = Sets.newHashSet();
+		Set<BlockPos> ends = Sets.newHashSet();
+		Set<BlockPos> add = Sets.newHashSet();
+		ends.add(new BlockPos(0, 0, 0));
+		boolean run = true;
+		
+		Mutable bPos = new Mutable();
+		
+		while (run) {
+			for (BlockPos center: ends) {
+				for (Direction dir: Direction.values()) {
+					bPos.set(center).move(dir);
+					BlockPos wpos = bPos.add(start);
+					BlockState state = world.getBlockState(wpos);
+					if (!blocks.contains(wpos) && canReplace.apply(state)) {
+						if (this.getDistance(bPos.getX(), bPos.getY(), bPos.getZ()) < 0) {
+							add.add(bPos.toImmutable());
+						}
+					}
+				}
+			}
+			
+			ends.forEach((end) -> blocks.add(end.add(start)));
+			ends.clear();
+			ends.addAll(add);
+			add.clear();
+			
+			run &= !ends.isEmpty();
+		}
+		
+		return blocks;
+	}
 }
diff --git a/src/main/java/ru/betterend/world/features/terrain/caves/TunelCaveFeature.java b/src/main/java/ru/betterend/world/features/terrain/caves/TunelCaveFeature.java
new file mode 100644
index 00000000..72826f16
--- /dev/null
+++ b/src/main/java/ru/betterend/world/features/terrain/caves/TunelCaveFeature.java
@@ -0,0 +1,54 @@
+package ru.betterend.world.features.terrain.caves;
+
+import java.util.List;
+import java.util.Random;
+import java.util.Set;
+import java.util.function.Function;
+
+import net.minecraft.block.BlockState;
+import net.minecraft.block.Blocks;
+import net.minecraft.block.Material;
+import net.minecraft.client.util.math.Vector3f;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.MathHelper;
+import net.minecraft.world.StructureWorldAccess;
+import ru.betterend.registry.EndTags;
+import ru.betterend.util.BlocksHelper;
+import ru.betterend.util.SplineHelper;
+import ru.betterend.util.sdf.SDF;
+
+public class TunelCaveFeature extends EndCaveFeature {
+	private static final Function<BlockState, Boolean> REPLACE;
+	
+	@Override
+	protected Set<BlockPos> generate(StructureWorldAccess world, BlockPos center, int radius, Random random) {
+		//OpenSimplexNoise noise = new OpenSimplexNoise(MHelper.getSeed(534, center.getX(), center.getZ()));
+		float rad = radius * 0.15F;
+		int min = MathHelper.ceil(rad) - 15;
+		int max = 31 - MathHelper.floor(rad);
+		List<Vector3f> spline = SplineHelper.makeSpline(0, 0, 0, 0, 0, 0, radius / 3);
+		spline = SplineHelper.smoothSpline(spline, 5);
+		SplineHelper.offsetParts(spline, random, 5, radius * 0.4F, 5);
+		for (Vector3f vec: spline) {
+			float x = MathHelper.clamp(vec.getX(), min, max);
+			float y = MathHelper.clamp(vec.getY(), -radius, radius);
+			float z = MathHelper.clamp(vec.getZ(), min, max);
+			vec.set(x, y, z);
+		}
+		SDF sdf = SplineHelper.buildSDF(spline, rad, rad, (vec) -> Blocks.AIR.getDefaultState());
+		Set<BlockPos> positions = sdf.setReplaceFunction(REPLACE).getPositions(world, center);
+		for (BlockPos p: positions) {
+			BlocksHelper.setWithoutUpdate(world, p, CAVE_AIR);
+		}
+		return positions;
+	}
+	
+	static {
+		REPLACE = (state) -> {
+			return state.isIn(EndTags.GEN_TERRAIN)
+					|| state.getMaterial().isReplaceable()
+					|| state.getMaterial().equals(Material.PLANT)
+					|| state.getMaterial().equals(Material.LEAVES);
+		};
+	}
+}