Lake Manapouri in the South Island contains some 34 islands, 22 of which are wooded. The largest of these is Pomona Island, which lies close to the centre of the lake. Other large islands include Holmwood island, Rona Island, and Mahara Island. The small settlement of Manapouri lies on the eastern shore between the inflow and outflow of the Waiau, and is a popular destination for tourists. The lake provides hydro-electric power via Manapouri Power Station, in West Arm, which discharges water through two 10-km tailrace tunnels to Doubtful Sound and the sea.