Lake Selfe, or Te Ruahikihiki in Māori, is a lake in the Selwyn District of the Canterbury Region in the South Island of New Zealand.

Geography Lake Selfe is situated in the Selwyn District between the Cottons Sheep Range, which reaches heights of up to to the south and west, and Mount Ida, which rises to to the north-northeast, as well as Little Mount Ida, which rises to to the east. The lake stretches at an elevation of and is approximately long in a northwest–southeast direction. At its widest point, it measures approximately in a southwest–northeast direction. The lake's circumference is approximately .Coordinates and longitude measurements were taken using Google Earth Pro version 7.3.4.8573 on 6 August 2022.

Lake Selfe is fed by a few streams and has its outflow—Moss Burn—at the northwest end of the lake. Its waters flow via Lake Henrietta into the Harper River.

Naming The original Māori name of the lake is Te Ruahikihiki. The European name given to the lake was for Henry Selfe, a member of the Canterbury Association.

See also List of lakes of New Zealand

References