Trail 5 leads down to the tunnel. The Tunnel is part of a construction project to build a railroad from the Ohio River, out of the Valley. They successfully completed an 'incline' in Madison, but this project went bust. I'd guess from the amount of rock work that was needed.
The Tunnel is the collapsed remains of an attempt to burrow through a cliff to keep the track from spilling into Clifty Creek. The work was hard and never was completed. Today, you can crawl through the tunnel from end to end. Take a flashlight and expect to get wet and muddy. The roof has fallen in several places and it is very narrow in spots. You'll have fun and on a hot summer day, you'll like to cool feeling you have after you've gotten out from the dark.
It you continue on trail 5 and then on trail 4, skipping the stairs at Lily Memorial Parking lot, where these two trail exit the canyon, you'll have a chance to see some more of the railroad project. Done where Hoffman Creek joins, a bridge was to be built. The block work is all that remains. By the way, the stairs at Hoffman Parking lot are fewer than back at Lily Memorial.
Trail #7 in the north picnic area provides the easiest access to Clifty Falls and Little Clifty Creek Falls. These are the 2 simplist to get to. Follow the paved trail out towards the point. There is an overlook from a gravel trail to the right (west) from which you can see Clifty Falls. This is the best you'll do if you're in a wheel chair or using a walker.
People with canes and stiff joints who can handle stairs can continue on down the trail and a series of wooden steps take you off the first small bluff (15' approx.) and down to a large trianglur ledge. Here trail 7 goes left and right and straight ahead. All directions lead to the edge.
Right takes you towards Clifty Falls. There are several places to view the falls and one that is a narrow ledged under a shelf. The rock railing feels secure and it deadends around a corner. It's the closest to the falls you can get.
If you take the left, or return from Clifty Falls along the rim trail, you'll come to Little Clifty Falls. Here the trail goes right down to the falls and a bridge takes you to the other side. Trail 7 returns to the picnic area by going up stream and crossing along with the parkway. You can return directly as you came after a pleasant walk and 2 water falls.
Most trails in the park are rugged as there are many steps up and down the canyon.
Trail #1 A short hike along the rim from the Nature Center. Stop and climb the tower on the point. We turned around there, but it continues to further up the road.
Trail #2 Except for the stairs into the canyon, this is a level walk, up Clifty Creek. Expect to get wet. And you'll need to decide which way to come back to the car.
Trail #3 From Hoffman Falls parking, it goes down to the falls, then south along a ledge towards the Nature center. It comes out at Trail #2 entrance and Trial #1's north end.
Trail #4 Leaves the Hoffman Falls parking and goes down past the falls to Clifty Creek. Then back to the ledge coming out at Lily Memorial parking.
Trail #5 From Tunnel Falls parking, it follows a ledge out and around Oak Grove Point (Shelter) coming out at the Lily Memorial. The Tunnel is here for your enjoyment. The Oak Grove Steps and the Lily Memorial Steps are the longest, so you might want do this with Trail #4
Trail #6 Is at the north end from Hickory Grove to Lookout Point. Moderate and short.
Trail #7 Begins and ends at the north picnic area. It provide access to 2 falls and a short walk along the east ledge of Little Clifty Creek
Trail #8 Follows the west ledge along Clifty Creek from the north Picnic area. Ends where Trail #2 enters the canyon near the Nature Center.
Trail #9 Connecting the Campground to the Pool and Nature Center. Moderate as it stays out of the canyon.
Trail #10 Short walk through the woods from the Pool parking area.