Derrybawn, Cullentragh Mountain, Mullacor, and Lugduff SE Top Loop

• 14.3 km / 8.9 mi total loop (not one way), starting and finishing at Upper Lake Car Park
• Typical time 5.5 to 6 hours, with about 5.8 hours a fair point estimate
• Difficulty 9/10: a serious full-day hillwalk needing strong fitness and reliable navigation
• Four named high points: Derrybawn Mountain 476 m, Cullentragh Mountain 467 m, Mullacor 661 m, Lugduff SE Top 638 m
• Elevation samples along the route run from 134 m to 632 m, so expect repeated climbing and descending rather than one single ascent (the listing reports about 806 m / 2,644 ft of gain)

From Upper Lake Car Park you pick up the Wicklow Way approach and climb through forest and woodland onto Derrybawn Mountain, where the ridge opens out above Glendalough. From there the route follows open mountain ground to Cullentragh Mountain, then turns up to Mullacor, the high point of the day, and on to Lugduff SE Top. The return uses the Wicklow Way / Red Route corridor back down to the Upper Lake, closing the circuit at the car park.

The payoff is the mix: framed views over the Lower and Upper Lakes from the Derrybawn and Lugduff side of the horseshoe, and broad open Wicklow mountain views from Mullacor and the connecting ridges.

• Rough, sometimes poorly defined mountain paths on the open ridge sections between the summits
• Boggy and wet ground is normal, especially around the saddles; expect mud on and near the Mullacor summit area
• Boardwalk on the Wicklow Way section helps across the wettest upland
• Forest and track sections near Glendalough at the start and finish
• Waterproof boots and gaiters are a reasonable default; trail runners will get soaked

Do not treat this as a waymarked walk. The Wicklow Way and Red Route parts are signed, but the open mountain link between Derrybawn, Cullentragh and Mullacor has patchy to poor path visibility and no consistent markers. Carry a map, compass and GPS track, and be confident using them in cloud. Much of the loop sits on exposed upland with no shelter, so wind and low visibility change the day considerably. Have a plan for turning back or shortening if the tops are clagged in.

Length, cumulative up and down across four summits, rough underfoot ground and real navigation demands stack up. If you want the lake views without the commitment, the 6 km Spinc short route is far easier and properly waymarked; this loop is more than twice the distance and a different order of effort.