The Sunken Reservoir

Green growth follows the mortar lines, thriving on no light at all. This is a great open hall, 4 by 4 paces. There is a hole in the floor, hand-sized, and it goes down further than seems reasonable. Chalk marks climb the wall in a column, gauging a water level that is no longer this high.

Depth 10.

You are reading the dungeon, not walking it. Rooms are only created by people, and only from inside the maze.