The main body of the lake runs north-south, and is 65 km in length. Three large fiords form arms to the lake on its western flank: North Fiord, Middle Fiord and South Fiord. These are the only inland fiords that New Zealand has, the other 14 are out on the coast. Several small islands lie in the entrance to Middle Fiord, which forks partway along its length into northwest and southwest arms. The surface of the lake is at an altitude of 210 m. It has a maximum depth of 417 m, so much of its bed lies below sea level, with the deepest part of the lake being 226 metres below sea level.