Glenmacnass Waterfall (, meaning The glen of the hollow of the waterfall) is an 80-metre high waterfall situated at the head of the Glenmacnass Valley in the Wicklow Mountains in Ireland. The Glenmacnass Waterfall is a popular tourist destination and scenic viewpoint area in the Wicklow Mountains. The Waterfall is bounded to the west by Tonelagee, and to the east by Scarr mountain. The entire Glenmacnass Valley can be accessed by the R115 road (also called the Military Road), which connects the Sally Gap in the north, to the village of Laragh in the south.