This loop showcases much of what makes hiking in the Gorge special. It takes you past three waterfalls, looks down into the slot canyon of Oneonta Gorge, and gives you a peek at the views over the Columbia River Gorge.
The loop can start at either the Oneonta trailhead (which is small with room for about 8 cars) or the larger lot a half mile away, Horsetail Falls. From the Horsetail Falls Trail, begin climbing some well-graded switchbacks. At the trail junction head right (east) on the Gorge Trail #400. After a few more switchbacks, the trail levels out above the Gorge. Shortly the trail leads to a gully containing Ponytail Falls. The trail drops into the green basin and is cut into the basalt flows cliff, taking you behind Ponytail Falls.
Continue to follow the trail west along the bluff. Take a minute to explore the short side trail that leads to Oneonta Bluff's clifftop viewpoint, you will see Beacon Rock and Hamilton Mountain to the east. The main trail continues into Oneonta Gorge and begins to descend. Look down at the narrow canyon of the namesake gorge, which is filled with water. The trail crosses Oneonta Creek on a metal bridge, which escaped untouched from the 2017 Eagle Creek Fire that devastated so much of the area. Above the bridge is Middle Oneonta Falls, a small drop that into the creek disappears over the edge into the canyon below. Soon after the bridge, the trail comes to a junction with the Oneonta Trail. For an optional bonus adventure, you can head left to Triple Falls, which will add another 1.8 miles and 300 feet of elevation to your day.
Otherwise, turn right to continue on your loop on the Oneonta Trail heading down to the highway. Once you reach the road take a right, make sure you check out the tunnel and walk the last half a mile back to your car. Use caution on the narrow road.
Note on the actual Oneonta Gorge -- the creek flowing through a slot canyon to Lower Oneonta Falls has its own sign and is located near Oneonta Tunnel. People enjoy taking the stairs down to the creek bed but, please be aware this route is NOT an official trail and it is not actively maintain it. The Forest Service recommends not going passed the large logjam, as there have been many injuries and a fatality in this area.