Gleniff Horseshoe

The Gleniff Horseshoe is a narrow road running about ten kilometres around a deep valley in the Dartry Mountains, enclosed on three sides by limestone walls with Truskmore and Benwiskin above. High on the headwall is a dark opening, Diarmuid and Grainne's Cave, associated with the legend of the couple who fled across Ireland from Fionn mac Cumhaill; local tradition makes this their last hiding place. Reaching it is a steep and loose scramble up scree and is not a marked route. The valley floor holds the ruins of a barytes mining operation - a mill and workers' buildings, worked into the twentieth century - and a ruined school. The road is single-track with grass in the middle and few passing places, and it is a working farming valley, so gates, livestock and slow vehicles are normal. There are no facilities anywhere on the loop.

What you'll find

• The amphitheatre - limestone walls closing the valley on three sides.
• The cave - the dark opening high on the headwall, and its legend.
• The mine ruins - barytes mill and buildings on the valley floor.
• Benwiskin - the tilted peak on the northern rim.

When to go

April to October. The valley is dark and enclosed under cloud. The road is difficult in ice or heavy rain and there is nowhere to turn on much of it.

What to expect

Single-track with almost no passing places and no facilities. The scramble to the cave is steep, loose and unmarked - people have needed rescue from it. Farm traffic and livestock on the road.

Nearby

Mullaghmore is north-west; Glencar Waterfall and Benbulbin are south.