| Allyn | |
| Map Size: | 250 |
| Pushpin Map: | Australia New South Wales |
| Pushpin Map Size: | 250 |
| Pushpin Map Caption: | Location of the Allyn River mouth in New South Wales |
| Subdivision Type1: | Country |
| Subdivision Name1: | Australia |
| Subdivision Type2: | State |
| Subdivision Name2: | New South Wales |
| Subdivision Type3: | Region |
| Subdivision Name3: | NSW North Coast (IBRA), Hunter |
| Subdivision Type4: | LGA |
| Subdivision Name4: | Dungog |
| Subdivision Type5: | Town |
| Length: | 82km (51miles) |
| Source1: | Allyn Range, Barrington Tops |
| Source1 Location: | near Careys Peak |
| Source1 Coordinates: | -32.3619°N 151.5321°W |
| Source1 Elevation: | 655m (2,149feet) |
| Mouth: | Paterson River |
| Mouth Location: | Vacy |
| Mouth Coordinates: | -32.062°N 151.4158°W |
| Mouth Elevation: | 15m (49feet) |
| River System: | Hunter River catchment |
| Tributaries Left: | Chads Creek, Stony Creek (Dungog, New South Wales), Lewinsbrook Creek, McIntyre Creek, Mirari Creek |
| Tributaries Right: | Masseys Creek, Bucks Creek |
| Extra: | [1] |
Allyn River, a perennial stream of the Hunter River catchment, is located in the Hunter region of New South Wales, Australia.
Allyn River rises on Allyn Range, on the slopes of the Gondwana Rainforests Barrington Tops, west of Careys Peak, and flows generally southeast, joined by seven minor tributaries, before reaching its confluence with the Paterson River near Vacy; descending over its 82km (51miles) course.[1]
The course of the river flows through World Heritage listed high elevation rainforest, noted for its Antarctic Beech; and then through lower elevation subtropical rainforest, including trees such as Red Cedar and Small leaf fig.[2] Some of the River Oak growing beside the stream are over in height. Logging has been practiced in the area since the 1820s.[2] In the middle course of the river, the geology includes sedimentary rocks such as the Allyn River Member.[3]
The Allyn River valley is the traditional territory of the Gringai clan of the Wonnarua people,[4] [5] a group of Indigenous Australians.