a drowned boy, either the son of 8th century Prince Cadwalader, murdered by a rival, or the son of 12th century Prince Owain Gwynedd and killed by his uncle. The traveller Thomas Pennant, writing in the 1780s, stated that the local shepherds were in awe of the lake believing it to be "the haunt of Daemons, and that no bird dare fly over its damned waters". Dinorwig Power Station Deep inside the mountain of Elidir Fawr there is a power station and many miles of tunnels. Dinorwig Power Station, a pumped storage hydroelectric facility, was originally built to provide back up facilities and water storage to smooth out the peaks and troughs in demand associated with the inflexible output of nuclear power stations. When demand is low, water is pumped up the mountain and stored in Marchlyn Mawr reservoir, previously a slate quarry. The water is released to flow through turbines during times of high demand for electricity. The power is conveyed through underground cables to join the grid so as to have little visual impact on the Snowdonia National Park skyline. Management The National Trust took over the management of the Glyderau and the Carneddau in 1951 in lieu of death duties on the Penrhyn Estate. The total area is about 7,000 hectares, half of which is common land with registered grazing rights for 45,000 sheep and 741 ponies. There are eight tenanted farms on the estate and the National Trust is responsible for the maintenance of footpaths and drystone walls, some of which date back many hundreds of years. The two mountain ranges form part of the Snowdonia National Park. Mountains in the Glyderau This is a list of the main summits in the range, in order from west to east. Elidir Fawr (924 m) Carnedd y Filiast (821 m) Mynydd Perfedd (813 m) Foel Goch (831 m) Y Garn (947 m) Glyder Fawr (1,001 m) Glyder Fach (994 m) Tryfan (918 m) Y Foel Goch (805 m) Gallt yr Ogof (763 m) Cefn y Capel (c.460 m ) References External links Walks in the Glyderau Capel Curig Llanberis Llanddeiniolen Llandygai Mountains and hills of Conwy County Borough Mountains and hills of Gwynedd Mountains and hills of Snowdonia