Llyn y Wrysgan is a former reservoir for the Wrysgan slate quarry. It's about 40 yards long and located to the south of the spoil tips and adits of the quarry. Most of the adits are open and accessible and can be explored - provided you have the right equipment and know what you're doing. A small car parking area can be found at Grid Ref : SH682454 (as for Llyn Cwmorthin), but the lane leading up to it is very steep and narrow. To reach the quarries and lake, follow the track towards Cwmorthin until you see a small reservoir on the left. Cross the stream after this and follow a path leading up to the workings. Llyn y Wrysgan lies just above the uppermost mine.
The Ffestiniog Railway's Tanygrisiau station is about a mile away.