The ruins of Hafna Mine are a fascinating legacy of an industry that once operated in the hills of the old Gwydyr Estate. Lead mining took place intermittently in the area from the early 1600s until the 1920s. Standing beside the lane that climbs to Llyn Sarnau, Hafna Mine, which still has its tall chimney, operated from 1879 util about 1915. There are several interpretative panels explaining the working of the mine, mill and smelter. A two mile walk called The Miners Trail starts from the car park at Llyn Sarnau and takes in Hafna Mine and other mining sites.