Lake Rotoiti, previously also known as Lake Arthur, is a small glacial lake near St Arnaud, on the edge of the Southern Alps. The lake was filled by a glacier at the end of the last ice age, about 15,000 years ago. As temperatures warmed the ice melted, and the depression was filled with water.
Being the third-largest lake in the Rotorua area, the lake also provides excellent fishing to both the shoreline and the boat angler who wishes to target trophy sized fish. Many thousands of fish are released into Lake Rotoiti each year and when combined with the wild fish population ensures that brown and rainbow trout stocks are very high.