The Lough Ouler and Tonelagee Loop is a moderate 5-mile looped trail that starts and ends in Brockagh, County Wicklow, Ireland. The trail, found in the heart of the Wicklow Mountains, is considered to be a moderate hike with a total elevation gain of 1589 ft, passing the well-known heart-shaped lake, Lough Ouler, taking in a river crossing and then a challenging but rewarding climb up to Tonelagee (2,680 ft), the third highest peak in the Wicklow Mountains. From the top, get the best view of the heart-shaped lake, and on clear days take in the impressive 360-degree views of the surrounding wild and beautiful Wicklow Mountains, however, expect changeable, inclement weather and bring layers for reaching the peak, as well as water and snacks.
The terrain is varied, from marsh and bog to mountain track and exposed hillside trail; the start of the trail tends to be wet and boggy even on dry days, so prepare for mud. Dogs are allowed in the Wicklow Mountains National Park but must be kept on a leash.