From Dunlavin it heads northeast, intersecting the N81 national secondary road near the village of Hollywood.

It then heads southeast, rising through the West Wicklow Mountains to the Wicklow Gap, the highest point on the road at 470m, before descending through the Glandasan Valley.

The 26 km (16 mi) section from Hollywood to Laragh is known as the Wicklow Gap Road (Irish: Bóthar Bhearna Chill Mhantáin) and it is one of only two routes crossing the Wicklow Mountains from east to west, the other being the road through the Sally Gap (Irish: Bearnas na Diallaite, meaning 'Gap of the Saddle') in North Wicklow.

During periods of off-peak electricity demand, water is pumped up from Lough Nathanagan, a corrie lake at the foot of Turlough Hill to an artificial reservoir at the top; when electricity demand is high, the water falls back through turbines inside the mountain to produce hydro-electric power for the national grid.

On a clear day from the summit of the Wicklow Gap (at Turlough Hill carpark) it is possible to look eastwards across the Irish Sea and view the mountains of Snowdonia in Wales.