This photograph shows an exterior view of a tunnel created for the Mangahao Line. This tunnel is just above the river level and has a bridge with rail tracks servicing the tunnel. The Mangahao Power Station provides hydroelectric power and is situated near the town of Shannon. It serves Wellington, Horowhenua, Taranaki, Hawkes Bay, and the Wairarapa. After being delayed by WWI, construction began in late 1919 and the station opened in November 1924.