The Stanley River is a river of the Canterbury Region of New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

's South Island

South Island

The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...

. An upper tributary of the Waiau River, it rises on the southern flanks of the St James Range and flows southwest to reach the Waiau 17 kilometres east of the Lewis Pass

Lewis Pass

Lewis Pass is a mountain pass in the South Island of New Zealand.The northernmost of the three main passes across the Southern Alps, it is higher than the Haast Pass, but slightly lower than Arthur's Pass...

. Lake Guyon

Lake Guyon

Lake Guyon is in the Canterbury Region in the South Island of New Zealand. The stream draining the lake feeds into the Waiau River.It was within the boundaries of the former St James Station but it is now surrounded by public conservation land. A backcountry hut is on its northern shore...

drains to the Stanley River via a swampy tributary named Stanley Vale. In its lower reaches the river passes through a gorge known as Stanley Gate.
The Fowler Pass Track follows the river for much of its length.