Horsetail Falls is one of those Gorge waterfalls that you can see from your car window at highway speed, which sounds like damning with faint praise but is actually remarkable. The 176-foot cascade drops off columnar basalt directly adjacent to the Historic Columbia River Highway, and the shape of the falls — wide at top, tapering as it falls — genuinely resembles a horse's tail, which is how these things get named.
The falls are worth stopping for on their own. But the short trail from the base earns the stop completely. A 0.4-mile climb up switchbacks through basalt and fern brings you to Ponytail Falls, also called Upper Horsetail Falls, which drops through a basalt overhang into a grotto behind which you can walk. The spray is significant. The acoustics inside the overhang are unusual. You're standing behind a waterfall in the Columbia River Gorge ten minutes from the parking area.
The Gorge produces this effect repeatedly — extraordinary natural features within easy reach of the Historic Highway, which was built between 1913 and 1922 specifically to give automobile travelers access to the landscape. The engineering of the highway is itself a historical artifact worth paying attention to.
Horsetail Falls is located between Multnomah Falls and Cascade Locks on the Oregon side. The parking lot is small and fills quickly in summer — go early or plan for a wait. The full Horsetail-Oneonta loop extending to Triple Falls adds 3.6 miles and considerable more climbing for those who want a longer day in the Gorge.