Parked at the lane-end above Glangors - permissive parking. Took the grass track up over the moor and down to the outflow of Llyn Cwm Silyn Isaf. Crossed with some difficulty over a loose stone wall. Then a steep ascent up in deep heather to the summit plateau, the going a little easier further up. Visited various boulders as possible HPs. Descended towards outflow of Llyn Cwm Silyn Uchaf - a bad mistake! This was ankle-breaking territory, with high heather, deep hidden holes and boulder fields. Don't go that way! Eventually reached the outflow, crossed easily, and took a faint path up past a ruin to re-join the grassy track back down to the car. Do not underestimate the roughness of this un-prepossessing hill, but with good views!