diff --git a/chunk.py b/chunk.py
index 977fdfa..9db1194 100644
--- a/chunk.py
+++ b/chunk.py
@@ -284,7 +284,14 @@ class ChunkRenderer(object):
             self._load_up_right()
         return self._up_right_blocks
     up_right_blocks = property(_load_up_right_blocks)
-    
+
+    def _load_up_right_skylight(self):
+        """Loads and returns lower-right skylight array"""
+        if not hasattr(self, "_up_right_skylight"):
+            self._load_up_right()
+        return self._up_right_skylight
+    up_right_skylight = property(_load_up_right_skylight)
+
     def _load_up_left(self):
         """Loads and sets data from upper-left chunk"""
         chunk_path = self.world.get_region_path(self.chunkX, self.chunkY - 1)
@@ -305,6 +312,13 @@ class ChunkRenderer(object):
         return self._up_left_blocks
     up_left_blocks = property(_load_up_left_blocks)
 
+    def _load_up_left_skylight(self):
+        """Loads and returns lower-right skylight array"""
+        if not hasattr(self, "_up_left_skylight"):
+            self._load_up_left()
+        return self._up_left_skylight
+    up_left_skylight = property(_load_up_left_skylight)
+
     def generate_pseudo_ancildata(self,x,y,z,blockid, north_position = 0 ):
         """ Generates a pseudo ancillary data for blocks that depend of 
         what are surrounded and don't have ancillary data
diff --git a/setup.py b/setup.py
index 0a36bcf..32360fb 100644
--- a/setup.py
+++ b/setup.py
@@ -55,7 +55,7 @@ except:
     pil_include = []
 
 c_overviewer_files = ['src/main.c', 'src/composite.c', 'src/iterate.c', 'src/endian.c']
-c_overviewer_files += ['src/rendermodes.c', 'src/rendermode-normal.c', 'src/rendermode-lighting.c', 'src/rendermode-night.c', 'src/rendermode-spawn.c']
+c_overviewer_files += ['src/rendermodes.c', 'src/rendermode-normal.c', 'src/rendermode-lighting.c', 'src/rendermode-night.c', 'src/rendermode-spawn.c', 'src/rendermode-cave.c']
 c_overviewer_files += ['src/Draw.c']
 c_overviewer_includes = ['src/overviewer.h', 'src/rendermodes.h']
 setup_kwargs['ext_modules'].append(Extension('c_overviewer', c_overviewer_files, include_dirs=['.', numpy_include] + pil_include, depends=c_overviewer_includes, extra_link_args=[]))
diff --git a/src/rendermode-cave.c b/src/rendermode-cave.c
new file mode 100644
index 0000000..85d7d93
--- /dev/null
+++ b/src/rendermode-cave.c
@@ -0,0 +1,190 @@
+/* 
+ * This file is part of the Minecraft Overviewer.
+ *
+ * Minecraft Overviewer is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * Minecraft Overviewer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with the Overviewer.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "overviewer.h"
+#include <math.h>
+//~ 
+//~ /* figures out the black_coeff from a given skylight and blocklight, used in
+   //~ lighting calculations -- note this is *different* from the one in
+   //~ rendermode-lighting.c (the "skylight - 11" part) */
+//~ static float calculate_darkness(unsigned char skylight, unsigned char blocklight) {
+    //~ return 1.0f - powf(0.8f, 15.0 - MAX(blocklight, skylight - 11));
+//~ }
+
+static int
+rendermode_cave_occluded(void *data, RenderState *state) {
+    int x = state->x, y = state->y, z = state->z;
+    RenderModeCave* self;
+    self = (RenderModeCave *)data;
+
+    /* check if the block is touching skylight */
+    if (z != 127) { 
+        
+        if (getArrayByte3D(self->skylight, x, y, z+1) != 0) {
+            return 1;
+        }
+
+        if ((x == 15)) {
+            if  (self->up_right_skylight != Py_None) {
+                if (getArrayByte3D(self->up_right_skylight, 0, y, z) != 0) {
+                    return 1;
+                }
+            }
+        } else {
+            if (getArrayByte3D(self->skylight, x+1, y, z) != 0) {
+                return 1;
+            }
+        }
+        
+        if (x == 0) {
+            if  (self->left_skylight != Py_None) {
+                if (getArrayByte3D(self->left_skylight, 15, y, z) != 0) {
+                    return 1;
+                }
+            }
+        } else {
+            if (getArrayByte3D(self->skylight, x-1, y, z) != 0) {
+                return 1;
+            }
+        }
+
+        if (y == 15) {
+            if  (self->right_skylight != Py_None) {
+                if (getArrayByte3D(self->right_skylight, 0, y, z) != 0) {
+                    return 1;
+                }
+            }
+        } else {
+            if (getArrayByte3D(self->skylight, x, y+1, z) != 0) {
+                return 1;
+            }
+        }
+
+        if (y == 0) {
+            if  (self->up_left_skylight != Py_None) {
+                if (getArrayByte3D(self->up_left_skylight, 15, y, z) != 0) {
+                    return 1;
+                }
+            }
+        } else {
+            if (getArrayByte3D(self->skylight, x, y-1, z) != 0) {
+                return 1;
+            }
+        }
+
+        /* check for normal occlusion */
+        /* use ajacent chunks, if not you get blocks spreaded in chunk edges */
+        if ( (x == 0) && (y != 15) ) {
+            if (state->left_blocks != Py_None) {
+                if (!is_transparent(getArrayByte3D(state->left_blocks, 15, y, z)) &&
+                    !is_transparent(getArrayByte3D(state->blocks, x, y, z+1)) &&
+                    !is_transparent(getArrayByte3D(state->blocks, x, y+1, z))) {
+                    return 1;
+                }
+            } else {
+                return 1;
+            }
+        }
+        
+        if ( (x != 0) && (y == 15) ) {
+            if (state->right_blocks != Py_None) {
+                if (!is_transparent(getArrayByte3D(state->blocks, x-1, y, z)) &&
+                    !is_transparent(getArrayByte3D(state->right_blocks, x, 0, z)) &&
+                    !is_transparent(getArrayByte3D(state->blocks, x, y, z+1))) {
+                    return 1;
+                }
+            } else {
+                return 1;
+            }
+        }
+        
+        if ( (x == 0) && (y == 15) ) {
+            if ((state->left_blocks != Py_None) &&
+                (state->right_blocks != Py_None)) {
+                if (!is_transparent(getArrayByte3D(state->left_blocks, 15, y, z)) &&
+                    !is_transparent(getArrayByte3D(state->right_blocks, x, 0, z)) &&
+                    !is_transparent(getArrayByte3D(state->blocks, x, y, z+1))) {
+                    return 1;
+                }
+            } else {
+                return 1;
+            }
+        }
+        
+        if ( (x != 0) && (y != 15) &&
+            !is_transparent(getArrayByte3D(state->blocks, x-1, y, z)) &&
+            !is_transparent(getArrayByte3D(state->blocks, x, y, z+1)) &&
+            !is_transparent(getArrayByte3D(state->blocks, x, y+1, z))) {
+            return 1;
+        }
+
+    } else { /* if z == 127 don't skip */
+        return 1;
+    }
+
+    return 0;
+}
+
+static int
+rendermode_cave_start(void *data, RenderState *state) {
+    RenderModeCave* self;
+    self = (RenderModeCave *)data;
+
+    /* first, chain up */
+    int ret = rendermode_normal.start(data, state);
+    if (ret != 0)
+        return ret;
+
+    /* if there's skylight we are in the surface! */
+    self->skylight = PyObject_GetAttrString(state->self, "skylight");
+    self->left_skylight = PyObject_GetAttrString(state->self, "left_skylight");
+    self->right_skylight = PyObject_GetAttrString(state->self, "right_skylight");
+    self->up_left_skylight = PyObject_GetAttrString(state->self, "up_left_skylight");
+    self->up_right_skylight = PyObject_GetAttrString(state->self, "up_right_skylight");
+
+    return 0;
+}
+
+static void
+rendermode_cave_finish(void *data, RenderState *state) {
+    RenderModeCave* self;
+    self = (RenderModeCave *)data;
+
+    Py_DECREF(self->skylight);
+    Py_DECREF(self->left_skylight);
+    Py_DECREF(self->right_skylight);
+    Py_DECREF(self->up_left_skylight);
+    Py_DECREF(self->up_right_skylight);
+
+    rendermode_normal.finish(data, state);
+}
+
+static void
+rendermode_cave_draw(void *data, RenderState *state, PyObject *src, PyObject *mask) {
+    /* nothing special to do */
+    rendermode_normal.draw(data, state, src, mask);
+    
+}
+
+RenderModeInterface rendermode_cave = {
+    "cave", "render only caves in normal mode",
+    sizeof(RenderModeCave),
+    rendermode_cave_start,
+    rendermode_cave_finish,
+    rendermode_cave_occluded,
+    rendermode_cave_draw,
+};
diff --git a/src/rendermodes.c b/src/rendermodes.c
index 0ef5550..08ac140 100644
--- a/src/rendermodes.c
+++ b/src/rendermodes.c
@@ -26,6 +26,7 @@ static RenderModeInterface *render_modes[] = {
     &rendermode_lighting,
     &rendermode_night,
     &rendermode_spawn,
+    &rendermode_cave,
     NULL
 };
 
diff --git a/src/rendermodes.h b/src/rendermodes.h
index 3027a7f..babc551 100644
--- a/src/rendermodes.h
+++ b/src/rendermodes.h
@@ -119,4 +119,18 @@ typedef struct {
 } RenderModeSpawn;
 extern RenderModeInterface rendermode_spawn;
 
+/* CAVE */
+typedef struct {
+    /* render blocks with lighting mode */
+    RenderModeNormal parent;
+    /* data used to know where the surface is */
+    PyObject *skylight;
+    PyObject *left_skylight;
+    PyObject *right_skylight;
+    PyObject *up_left_skylight;
+    PyObject *up_right_skylight;
+    
+} RenderModeCave;
+extern RenderModeInterface rendermode_cave;
+
 #endif /* __RENDERMODES_H_INCLUDED__ */