| Glendalough Upper Lake | |
| Pushpin Map: | Island of Ireland |
| Pushpin Map Alt: | Lough Arrow location in Ireland |
| Pushpin Label Position: | none |
| Pushpin Map Caption: | Location in Ireland |
| Location: | County Wicklow |
| Coords: | 53.0028°N -6.3658°W |
| Type: | Glacial lake |
| Inflow: | Glenealo river, Lugduff Brook |
| Outflow: | Glenealo river |
| Basin Countries: | Ireland |
| Length: | 1.4km (00.9miles)[1] |
| Width: | 0.52km (00.32miles) |
| Max-Depth: | 30m (100feet) |
| Elevation: | 440feet[2] |
| Islands: | no |
Glendalough Upper Lake ([3]) is a glacial lake near Glendalough, County Wicklow, Ireland.
The lake is located in the Wicklow Mountains area west of Glendalough Early Medieval monastic settlement.[4] Near the southern shore stands a small rectangular church named Temple-na-Skellig, only accessible by boat and a series of steps from the landing stage; a nearby cliff hosts a cave called St. Kevin's bed,[5] reputedly a retreat for St. Kevin and later for St. Laurence O'Toole.
The lake is classified as a ribbon lake. The Upper and the Lower lake were at first united but one of their inflow brought an amount of sediment large enough to divide the original lake in two parts.[6]
Close to the eastern tip of the lake passes the Wicklow Way, a long distance waymarked walking trail, on its way from Rathfarnham in the north to its southerly point of Clonegal.[7]
The Upper Lake is part of the Wicklow Mountains National Park. Among the plants living near the coast can be cited the white waterlily and the broad-leaved pondweed. Some of its shore is occupied by a marsh with horsetail, bottle sedge and common reed, which is a convenient place to spot dragonflies.