Llyn Glas (the blue pool) is almost hidden and its colour is amazing. It is very clear and the bed of the lake is bright blue in the centre with strong green plant growth around the margins. The water here is stained blue probably due to copper contamination, so is unlikely to be a good habitat for wild brown trout, however it has been reported that they are present in low numbers.

The llyn is said to be free fishing. We have been unable to locate any contact details, so we recommend anglers enquire locally.