Nature expert Iolo Williams visits Padarn Country Park near Llanberis in Snowdonia. Created on the site of an old slate quarry, the park is set in a stunning landscape surrounded by the highest mountains in Wales. Ring ouzel, one of the most sought-after birds in the whole of the UK, sing above the old slate tips, and wood warblers and pied flycatchers have established territories in the park's ancient woodland that's remarkably survived two centuries of mining. Hidden in the woodland are derelict buildings, once used to store gunpowder, and the old quarry work levels are favourite places for slow worms - our legless lizards. The trains of the old quarry have also survived and have been lovingly restored by Llanberis Lake Railway. Llyn Padarn is the second largest natural lake in the whole of Wales and is one of the prime spots in Snowdonia for water sports, but by night otters use the lake and the deep water is home to Arctic char fish.