Underground River
=================

+-- Level +3 ---------------------------------------------------------------------------------+
|                                                                                             |
|   %                                                                                         |
|   vv                                                                                        |
|                                                                                             |
+---------------------------------------------------------------------------------------------+

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

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

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

+-- Level -1 ---------------------------------------------------------------------------------+
|                                       ^                                                     |
|                                       M                                                     |
|                                                                                             |
+---------------------------------------------------------------------------------------------+