Large Black Cave
================

+-- Ground level --------------+
|                              |
|        <*--*                 |
|             \                |
|              \               |
|               *              |
|                \             |
|                 \            |
|                  *           |
|                 /|           |
|                / |           |
|               *  *           |
|              /    \          |
|             /      \         |
|         *  *        *--*     |
|        / \ |            \    |
|       /   \|             \   |
|      *     *     M        *  |
|             \    v\       |  |
|              \     \      |  |
|               *     *     *  |
|              /      |    /   |
|             /       |   /    |
|         *--*        *  *     |
|             \      /   |     |
|              \    /    |     |
|   *--*        *--*     *     |
|       \           \   /      |
|        \           \ /       |
|         *--*        *        |
|             \      /         |
|              \    /          |
|               *--*           |
|              /               |
|             /                |
|         *--*                 |
|                              |
+------------------------------+