Urban Spelunking.

Ever wonder where stormwater goes? Me too.

The most common material you see are these standard concrete pipes.

It helps to bring a map, and a friend.

Junctions between pipes are often made of this corrugated steel. It's a bit worrying when it flattens under the weight of the road above it.

New construction sometimes has this sort of rectangular pipe. Easy walking!

As we travel to older parts of the city, the infrastructure gets more interesting.

Much more interesting! Look out for bats.

At last - the end of the first tunnel. At this point, you start seeing fish and other aquatic creatures.

It opens out to a creek bed.

Another tunnel, working our way upstream.

The drains get smaller as you travel away from the outflow.

Too small! Time to pop out and take the rest of the trip above ground.