The Southfury River is likely Kalimdor's most prominent river. Beginning from a lake in Mount Hyjal, it drops into the regions below via a set of spectacular waterfalls. The resulting wide, swiftly-flowing river forms the boundary between the forest of Ashenvale and Azshara, and further south, the border between the Northern Barrens and Durotar. During the Cataclysm the river overflowed into parts of western Durotar, causing the flooded area to be renamed Southfury Watershed. The river empties into the Great Sea in a cascading waterfall just northeast of the goblin port city of Ratchet.
There are three bridges that span the Southfury River: one crossing from Azshara into Ashenvale, one leading into the Horde's capital city of Orgrimmar, and one that crosses from Durotar into the Northern Barrens. Notably, just north of the western bridge of Orgrimmar, there is a spot on the river where four in-game zones meet: Ashenvale, Azshara, Durotar, and Northern Barrens.
A goblin named Horton Hornblower sits at a dock near the mouth of the Southfury with his Riverboat. After doing quests for the goblins in Ratchet, he offers , which provides transportation to the area outside Nozzlepot's Outpost in the Northern Barrens.
The Bilgewater Cartel goblin's project in Azshara tainted the Southfury River, and when the Cataclysm hit the polluted river flooded western Durotar, creating the Southfury Watershed. It could still be used to water the crops, but it could no longer be drunk.
In the RPG
The Southfury River forms a natural border between the northeastern part of the Barrens and the western portion of Durotar, with the later being a long expanse separated from mainland Kalimdor by the Southfury River.