Culverts and storm drains provide an opportunity to move about undetected…if you’ve got the nerve.

They may also lead you to water.

If you live in a city, you routinely walk and drive over a plethora of tunnels. Some of them contain wires and other infrastructure. Some carry sewage and wastewater. Others conceal buried rivers or carry storm water.

There’s an entire subculture dedicated to the art of urban exploration… going into places where you shouldn’t be, often abandoned or empty. And, within that subculture is a niche dedicated to drains.

https://uer.ca/uec/_uec/drains.html

The article above goes into substantial detail about drain exploration, including the challenges of potential oxygen deprivation and the importance of sturdy flashlights that won’t break or get waterlogged if you drop them.

It also points out that the water you find in a storm drain may include toxic chemicals as the result of illegal dumping. If you do get water from a storm drain, be sure to run it through a sturdy water filter before drinking.

I went into a storm drain once on a dare. Underground, we turned off our flashlights and were enveloped by the deepest, densest darkness I’ve ever experienced. It was very serene.

You can find maps of underground infrastructure at your city hall, although you may have to pay for them. If you’re interested, I recommend starting by looking for any urbex sites about your area, or historical records of buried rivers. Alternately, you could just go to a ravine or park area with a culvert opening and start from there.