Renowned for it’s magnificent scenery, Glendalough derives its name from the Irish ‘Gleann dá Locha’, or ‘valley of the two lakes’. It is a glacial valley formed during the last ice age. In addition to the natural beauty of the two lakes- upper and lower and the surrounding mountains, the valley is also home to one of Ireland’s most impressive monastic sites founded by St. Kevin in the 6th Century. All these combine to make this the most visited areas in the Wicklow Mountains National Park
The Glendalough Valley is deep and narrow with the typical U-shape typical of those carved out by glaciers during the last Ice Age. Originally Glendalough was made up of one lake only but Lugduff Brook flowed into the middle of the lake depositing sediments that accumulated over time dividing the lake into the two we know today. (The lawns and car park at the Upper Lake now sit on top of these deposits!). The valley is surrounded by high mountains with summits rising over 650 metres (2132 feet) and the Upper Lake, the larger of the two, is 30 metres deep at its deepest point.
Nature of Glendalough
The lakes in Glendalough are more diverse in character than the higher altitude mountain corrie lakes such as Upper Lough Bray, although still naturally low in nutrients and therefore not naturally home to the diversity of species of lowland lakes. The area is a designated nature reserve and also part of the Wicklow Mountains Special Area of Conservation under the European Habitats Directive. The acidic water of the Upper Lake is deep and contains only a few plant species such as white water lily, pondweed and bulbous rush. At the upper end where the lake becomes shallower, a marsh has formed which is home to Horsetail, Common Reed and Bottle Sedge. This is also the best area of the Park to spot dragonflies. Close to the monastic ruins, heath Orchid, Horsetail and Marsh Violet appear annually in the marsh and fen fringing the Lower Lake. Read more about the lakes of the Wicklow National Park here.
The lakes are surrounded by semi-natural sessile oak woodland. Much of this was formerly coppiced (cut to the base at regular intervals) to produce wood, charcoal and bark. In the springtime, the woodland floor is carpeted with bluebells, wood sorrel and wood anemone. The understorey is largely comprised of holly, hazel and mountain ash, with other common plants including woodrush, bracken, polypody fern and various species of mosses and lichens.
Deer and badgers are common in the woodlands around the lakes and otters feed in the lakes and river. Bats are also common in the valley. The birch and willow woodlands around the Lower Lake are good for spotting Reed Bunting and Willow Warblers. At the edge of the lakes, Grey Herons are common, standing motionless ready to spear a passing trout. Out on the lakes look out for Goosanders or Greylag Geese. Raven and peregrine breed on the cliffs above the Upper Lake and the rare ring ousel can be seen by a keen eye on the higher ground in spring and summer. Whooper swans are also present on the Upper Lake some winters.
For many, with such a splendid setting and with history and nature all around you, enjoying Glendalough is simple – Wander along the lakeshores, take in the special atmosphere and sit by the lake relaxing. For the more active, the valley is place to be explored.
Due to the sensitive nature of the lakes and their designation as a nature reserve, many water based activities are restricted on the Upper and Lower lakes. Canoeing, kayaking, power boating, water-skiing and jet skiing are not permitted. Swimming, though prohibited, is a common activity in the Upper Lake during the summer. This is not advised however, since the water is extremely cold, the bank shelves steeply and there is no lifeguard on duty.
Glendalough Upper and Lower Lakes are occasionally fished. Fishing is permitted from 15th March to 30th September using artificial lures only. The waters in the Park are very low in nutrients and the average size of trout is very small at 15-18 cm (6-7 inches). All fish under 20.5cm (8 inches) must be returned unharmed.
The best way to enjoy the lakes of Glendalough is from the many well-designed and maintained designated walking trails. You can take a walk along the lakeshore or hike high up into the mountains for spectacular views of the lakes and valley. Walks vary from a few short flat kilometres to 14 km. Trail maps and general information for walkers are available here. Dedicated nature trails have also been designed so whether you are interested in birds, bugs or flowers, there is a walking trail to bring you close to the nature of the lakes.
More information on recreational activities in Glendalough, including what is permitted is available here.
In addition to the spectacular natural heritage of the valley, Glendalough has fascinating human history. It is one of the most important monastic settlements in Ireland and also has a significant mining heritage dating back to the 1790’s where lead, zinc and silver were mined. Read more on the history of Glendalough here.