Underwater Passage
==================

+-- Level +1 ------------------------+
|                                    |
|               *--*--*              |
|              /      |              |
|             /       |              |
|            %        *              |
|            v        |              |
|                     |              |
|                     *              |
|                     v              |
|                                    |
+------------------------------------+

+-- Ground level --------------------+
|                                    |
|                  %--*              |
|                  v   \             |
|                       \            |
|                        *           |
|                        |           |
|            ^           |           |
|            %           *           |
|           / \          |           |
|          /   \         |           |
|         *     *--*     *           |
|         |         \   /            |
|         |          \ /             |
|         *           *              |
|        /            |              |
|       /             |              |
|      *              *              |
|      |             /               |
|      |            /                |
|      *        *--*                 |
|       \      /                     |
|        \    /                      |
|         *--*                       |
|                                    |
+------------------------------------+

+-- Level -1 ------------------------+
|                                    |
|                     *--*--*--*     |
|                    /          \    |
|                  ^/            \   |
|                  %              *  |
|                  |              |  |
|                  |              |  |
|                  *              *  |
|                 /              /   |
|                /              /    |
|               *           *--*     |
|               |          /    \    |
|               |         /      \   |
|               *        *        *  |
|                \      /         |  |
|                 \    /          |  |
|                  *--*           *  |
|                                 |  |
|                                 |  |
|               *                 *  |
|              / \               /   |
|             /   \             /    |
|            *     %        *--*     |
|            |     v       /         |
|            |            /          |
|            *           *           |
|             \         /            |
|              \       /             |
|               *--*--*              |
|                                    |
+------------------------------------+

+-- Level -2 ------------------------+
|                                    |
|      *--*--*           *--*--*     |
|     /       \         /      |     |
|    /         \       /       |     |
|   *           *     *        *     |
|   |            \   /         |     |
|   |             \ /          |     |
|   *              *           *     |
|   |              |          /      |
|   |              |         /       |
|   *              *        *        |
|    \             |       /         |
|     \            |^     /          |
|      *--*--*     %--*--*           |
|             \                      |
|              \                     |
|               *                    |
|               |                    |
|               |                    |
|               *                    |
|              /                     |
|             /                      |
|            M                       |
|                                    |
+------------------------------------+