The central river flows down from the Silver Slopes, and its name requires no explanation to anyone who sees it at midday. The riverbed is dense with mica, pyrite, and actual silver flake—runoff from the mining operations around Sweivyon. When the sun hits the water at the right angle, the entire river blazes with reflected light, visible for miles.
Sweivyon has built its economy partly on controlling Sunbeam River access. The city-state operates a series of sluice gates and settling pools upstream, capturing the heavier metals before they wash out to sea. What escapes the sluices supports a secondary economy of "glitter-panners"—independent prospectors who work the lower river and strait-mouth, recovering what Sweivyon's filters miss.
The Sunbeam is navigable for shallow-draft vessels up to about fifteen miles inland, where rapids begin. A portage road connects the navigable lower river to Sweivyon proper, facilitating the silver trade. The river-mouth settlement of Glintwater serves as Sweivyon's de facto port.