Do you like the dark? This is the place for you. This tunnel was built from 1912 to 1914 and is 2 mi. long. During 95% of the hike you can't see your hand in front of your face. A flashlight is a must....but it doesn't get rid of the creepy feeling. There are all kinds of slimmy algae and fungi,(of unpleasant colors), hanging from the ceiling and oozing down the walls. You hear dripping water and every sound is distorted and muffled. You smell musty dirt. Strange electronic contraptions of the past are occasionally in the niches along the way. Your imagination runs wild with thoughts of things real and unreal. Finally you reach the end and step into the light....but then you have to go back... Hope your batteries hold out.....Ooooooooooo!!!