Looking across Llyn Peris to the vast remains of the Dinorwig Slate Quarry. It is a large former slate quarry, now home to the Welsh National Slate Museum, located between the villages of Llanberis and Dinorwig in north Wales. It was the second largest slate quarry in Wales, indeed in the world, after the neighbouring Penrhyn Quarry. It covered more than 700 acres (2.8 km2) consisting of two main quarry sections with 20 galleries in each and a number of ancillary workings. Extensive internal tramway systems connected the quarries using inclines to transport slate between galleries.
At its peak in the late 19th century, “when it was producing an annual outcome of 100,000 tonnes”, Dinorwic employed over 3,000 men and was the second largest opencast slate producer in the country. Although by 1930 its working employment had dropped to 2,000, it kept a steady production until 1969.