|Between Logan Rd and London Ln along Hwy 71 look for the Tunnel Trail Campground.
This is a privately run campground, but you may park along the fence
along the miniature golf course for the time it takes you to go find
this box. Just to be sure, I would suggest that you "check-in at the
office" and ask if it is okay to park there to hike down to the tunnel.
We did, and there was no problem at all.
There is no where to park closer to Tunnel #1 and still be able to easily walk there, unless you want to climb up/down cliffs. From the campground, it is a 1.25 mile walk one-way to the tunnel. It took us just under two hours to complete everything we did.
From the picnic table between the office and the miniature golf course, if you look back towards the bike trail, you'll see a sign with lots of arrows telling you how far various places along the trail are from the campground and in what direction. This will tell you which direction to go to get to Tunnel #1 (south if the signs are missing). Walk all the way to the tunnel. Remember to stay to the right side of the trail so bikers can pass. (You'll be close to the tunnel when you get to the picnic table where there used to be a side track and water tower for the trains.)
When you get to the tunnel, as always, walk all the way through, preferably without a flashlight! Stop when you get to the opposite mouth of the tunnel. Turn around and face the inside of the tunnel at its mouth. Looking to your right, notice that the bottom of the door has a flap, and where it meets the outside tunnel wall, there is some poured concrete support. The box is located in a hole under this concrete behind a couple of rocks and the flap. Be sure no one is around watching you get the box or put it back. Be sure to hide the box with the rocks and dirt so it looks natural! Thanks!
Note: Look for clues to a bonus box!
Before you set out read the waiver of responsibility and disclaimer.