I can't share much detail for fairly obvious reasons and there isn't much of a story. It was just 4 guys riding bikes in pipes. They are huge and interesting in there own creepy way. We ride about 5 miles of them.
Some very old brick. This is the end of the line. The drain beyond is too small.
More very old stone and barrel vault ceilings.
Grade changes create water falls as well as drain pipes that ruptured due to ground water.
Don't try this yourself. Your results may very. Close cover before striking. For external use only! Do not use near open fire. Not suitable for children. Not for human consumption. Warning: May contain nuts. Not dishwasher safe. 99.9% inert ingredient. No purchase necessary.