Hoka Kura is a cold inland oligotrophic lake formed approximately 18,000 years ago. It fills a trough 9.7 km (6.0 mi) long by 2.4 km (1.5 mi) wide, within the glacially-carved Hurunui River Valley. The North Branch of the upper Hurunui River enters the lake via a shingle delta at the northwestern end and drains through a narrow natural channel at the southeastern end of the lake.[3]