Armu (Russian: Арму) is a river in Krasnoarmeysky District of Primorsky Krai, a tributary of Bolshaya Ussurka River.
It is 201 kilometres (125 mi) long. The river's drainage basin covers about 5,424 square kilometres (2,094 sq mi). The longest tributary of the Armu is the Obilnaya River, 101 kilometres (63 mi) long.
The river is a popular place of tourism and fishing. One of sort of vodka has been named after it.
Coordinates: 45°45′47″N 135°28′02″E / 45.76306°N 135.46722°E