The easternmost river has earned its grim name honestly. It flows through the Glass Fields—a stretch of volcanic obsidian that the Sundering exposed and subsequent eruptions expanded. The riverbed is littered with natural glass shards ranging from pebble-sized splinters to blade-length fragments, all edges keen enough to slice leather.
No one boats the River of Blades. The glass would shred any hull within minutes. Fording is possible only at specific points where the Fengruk have laid down iron grates, and even then, a fall means cuts that take weeks to fully heal. The river runs red after storms, not from mineral content but from the blood of animals foolish enough to drink from its banks.
Despite—or because of—its dangers, the River of Blades attracts a specific clientele. Weaponsmiths prize volcanic obsidian for certain ritual blades, and the Glass Fields produce some of the finest natural specimens in Alaria. Collection expeditions from Durkarn make the journey several times a year, harvesting glass under the protection of heavily armored handlers. The obsidian trade is small but lucrative.
The river empties into the strait through a delta of black sand—pulverized glass worn down by the current. The delta settlement, if it can be called that, is a seasonal camp of obsidian traders and the few pilots willing to navigate the eastern strait channels. They call the place Blackmouth, and it has no permanent structures.