Tunnel Drive Trail is located just west of Cañon City. It is a spectacular 2 mile (4 miles round trip) trail that passes through three tunnels bored through solid granite, traverses a couple of bridges, and ends just short of the Royal Gorge. This cache is one mile from the trailhead. The first 0.2 mile is uphill, and the trail is almost level after that. The cache is about 200 feet off the trail and requires navigating some steep terrain and avoiding a cactus minefield. No scrambling is required if you pay attention to your route.
This trail was originally the route of a pipeline that carried water from the Royal Gorge to Cañon City. You can see many remnants of the old water pipeline that ran along, and sometimes under, the trail. The pipeline was abandoned in the 1960s after a more modern facility was built.
The cache is big enough for trade items and travel bugs. There is a nice FTF prize.