Lava Tube
=========

+-- Level +5 ---------------------------+
|                                       |
|         *--*--*                       |
|        /      |                       |
|      ^/       |                       |
|      %        *                       |
|              / \                      |
|             /   \                     |
|            *     *                    |
|            |                          |
|            |                          |
|            %                          |
|            v                          |
|                                       |
+---------------------------------------+

+-- Level +4 ---------------------------+
|            ^                          |
|         *--%                          |
|        /                              |
|       /                               |
|      *                                |
|      |                                |
|      |                                |
|      %                                |
|      v                                |
|                                       |
+---------------------------------------+

+-- Level +3 ---------------------------+
|                                       |
|         *                             |
|        / \                            |
|       /   \                           |
|      *     *                          |
|      |                                |
|      |^                               |
|      %                                |
|     /                                 |
|    /                                  |
|   *        *--%                       |
|    \      /   v                       |
|     \    /                            |
|      *--*                             |
|                                       |
+---------------------------------------+

+-- Level +2 ---------------------------+
|               ^                       |
|               %--*--*--*              |
|                        |              |
|                        |              |
|                        %              |
|                        v              |
|                                       |
+---------------------------------------+

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

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

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

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

+-- Level -3 ---------------------------+
|                                       |
|                        M              |
|                        |              |
|                        =              |
|                        *              |
|                        |              |
|                        =              |
|                        *              |
|                        |              |
|                        |^             |
|                        %              |
|                                       |
+---------------------------------------+