Usk Reservoir: Circular Walks
Completed in 1955, The Usk Reservoir now covers some 280 acres (110 ha) of land. So when you walk around it in a couple of hours, you are covering a fair amount of ground. There are not many reservoirs you can so conveniently walk around in a couple of hours or so. The scenery looking back towards the Castle (the mountains in the background in the above picture are the mountains just north of the Castle) is most impressive.
The Reservoir is just off the minor road between Trecastle and Llanddeusant, 7 miles (11 km) west of Sennybridge and not too far from Craig y Nos Castle if you go along the Trecastle Mountain road. It will take about 30 minutes at most, by car, to get here from the Castle.