[6] Formed by the confluence of its east and south forks, the Matanuska River flows generally southwest to the Knik Arm of Cook Inlet.

[6] The main stem is silty with glacial run-off from spring through fall but at lower flows beneath winter ice, it runs relatively clear.

Accessible at several bridges and other points along the Glenn Highway, the Matanuska varies from Class II (medium) to III (difficult) on the International Scale of River Difficulty.

Expert paddlers sometimes run a tributary, Caribou Creek, that flows past Matanuska Glacier and is rated Class II to IV (very difficult).

Hazards along the main stem include swift, cold water; big standing waves and holes along some sections; overhanging or submerged vegetation on the lower reaches, and upriver winds.