The Waimakariri River is Canterbury's longest waterway and measures almost 150 km in total. It is formerly known as Courtenay River, and locals may refer to it as the "Waimak". The Waimakariri originates nearly eight kilometres south of Arthur's Pass and flows through Canterbury towards the Pacific Ocean north of Christchurch.
The Waimakariri Gorge is a narrow ravine that the river runs through near Sheffield. The river is of high importance for the Canterbury Plains, as it provides huge amounts of freshwater for New Zealand's agriculture.