Over the weekend, I did some hiking on a “new to me” trail – it had tunnels and all! The Flume Trail, however, is far from new in the grand scheme of things. Now open only to foot travel, the fantastic hiking trail follows the route of the historic Rockerville Flume – an 1880’s gold-rush era water channel used for placer mining.

The Flume Trail (trail #50), as it exists today, is a 16.5 mile trail that runs ever-so-gently downhill from Sheridan Lake Dam to the old gold-mining town of Rockerville. The trail is easy to follow and well marked by tree blazes, numbered “50″ trail markers and distinctive red, white and blue National Recreation Trail notices.

The Flume’s recognition as a National Recreation Trail is easy to understand as remnants of the original man-made aqueduct line portions of the trail. Wooden planks, some with square nails still embedded, rest peacefully along the trail – serving as a reminder of the historical significance of the trail route.

It’s because of the important role the flume played in Black Hills history that the trail has been limited to hiking only. Some of the remaining artifacts along the trail could be easily damaged by motor vehicles, bicycles or even horses.

One of the most unique things about the Flume Trail is the fact that the two original flume tunnels straight through the hills are open as an active part of the trail. The tunnels were blasted and drilled through the surrounding metamorphic schist rock, which is estimated to be about 1.7 billion years old. Yes, billion – with a “B.”

The tunnels remain much as they were back in the 1880s when the flume carried the gold-revealing water through them. Entrances to the tunnels were rebuilt in 1985 and enforced for hikers’ safety. In case smallish dark tunnels aren’t quite your thing, there are alternate routes up and over rather than through the mountain.

I must admit – hiking through the low tunnels was a bit eerie, but definitely worth it. I filmed my way through the second of the two that was about 100 feet long.

If you do get the opportunity to hike the Flume Trail, I highly recommend braving your way through the tunnels. But just in case you never get the chance, the video above will at least let you say you’ve seen the inside – sort of.