Waiau Toa / Clarence River

Waiau Toa / Clarence River
The Waiau Toa / Clarence River, as viewed from State Highway 1 near the river's mouth
The Waiau Toa / Clarence River system.
Native name	Waiau Toa (Māori)
Location
Country	New Zealand
Regions	Canterbury, Marlborough
Physical characteristics
Source	Clarence Pass
• location	Spenser Mountains
• coordinates	42°6′14″S 172°42′58″E / 42.10389°S 172.71611°E / -42.10389; 172.71611
Mouth	Pacific Ocean
• location	Clarence
• coordinates	42°10′S 173°57′E / 42.167°S 173.950°E / -42.167; 173.950
• elevation	Sea level
Length	209 km (130 mi)
Basin features
Tributaries
• left	Acheron River, Dillon River, Gloster River, Bluff River
• right	Styx River, Hossack River
Waterbodies	Lake Tennyson

The Clarence River (Māori: Waiau Toa; officially Waiau Toa / Clarence River) is a major river which flows through the Kaikōura Ranges in the northeast of New Zealand's South Island. At roughly 209 kilometres (130 mi) long, it is the longest river in Canterbury and the eighth longest in New Zealand.

For its first 50 kilometres (31 mi), the river runs in a generally southeastern direction. It then turns northeast, running down a long straight valley between the Inland and Seaward Kaikōura Ranges. At the end of the Seaward Kaikōuras, the river meanders through undulating hill country before draining into the Pacific Ocean near the town of Clarence. A large part of the river is within the boundaries of Molesworth Station.

The river and its tributaries cut through rock formed on the seafloor of the Pacific during the late Cretaceous through to the middle Eocene, during which period the majority of New Zealand was at points almost entirely submerged.^[1] This provides a useful record of this time period, and has contributed to our understanding of several events which took place during that era.^[2][3][4] The area also provides valuable insight into more recent geological events, having been heavily affected by the 2016 Kaikōura earthquake.