The Eglinton River West Branch drains south through Fiordland in New Zealand's South Island, originating at Lake Fergus and flowing roughly 50 kilometres before the full Eglinton River reaches Lake Te Anau. The river runs alongside State Highway 94, the Te Anau–Milford Highway, making access relatively straightforward along much of its length.

The West Branch is generally rated Grade I to II. The middle reaches below the confluence with Mistake Creek are almost entirely Grade I, offering straightforward paddling. There are short gorges present between Lake Gunn and Cascade Creek, and again below the junction with Walker Creek, which paddlers should be aware of when planning their route.

Water levels are an important consideration. Flow leaving Lake Gunn is small and is substantially increased by Cascade Creek, which joins just south of the lake. Despite this, there is not usually sufficient water at the Cascade Creek confluence to support kayaking, and paddling is more commonly undertaken from the junction with the East Branch further downstream. Those planning to paddle the upper West Branch sections should check flows carefully before committing to a put-in.

The river corridor passes through the Fiordland landscape, with tributaries including Cascade Creek, Plato Creek, Smithy Creek, Kiosk Creek, Wesney Creek, Black Creek, Mistake Creek, Hut Creek, Waterfall Creek, and Murcott Burn feeding into the West Branch along its course. The area is known for its lush forest environment typical of Fiordland.