The Treadwell operated from 1882 to 1922 and during its peak years was the world's largest gold mine. The bustling Treadwell wharf at Douglas, Alaska welcomed steamships, freighters, and ferries. The Pump House was constructed in 1914 at the end of a 600-foot long pier. The building's three centrifugal pumps lifted 2,700 gallons of water a minute from Gastineau Channel and the salt water was used to flush mill tailings back to the shoreline. There is now an 80-acre, 2-mile long sand beach consisting mostly of mine tailings from the Treadwell. The massive cave-in of 1917 resulted in the closing of three of the Treadwell's mines. The fourth ceased operation in 1922. The Pump House is one of the few remaining structures and serves as a visual reminder of the area's rich history. Read more here and here. Click here to download the CoastView app and explore the remains of the Pump House.