Midbay and Nyr Dyv
The blue expanse of the Nyr Dyv is the largest known fresh-water lake upon Oerth. Midbay, where the waters of that lake gather to form the Selintan River, is one of its most placed regions.
The Nyr Dyv has three major inlets ( the Artonsamay, Veng, and Velverdyva Rivers ), and an outlet greater than the Selintan in the Nesser River. All of these are even more navigable than the Selintan, and thus the lake has become a major center of commerce in the known world.
Monsters of a variety of horrid types are known to dwell in the Nyr Dyv's darkest reaches (its name means "Lake of Unknown Depths"). Fortunately, the shallow waters of the Midbay seem to prevent these creatures from intruding there.
Naval fleets from several bordering nations patrol the waters of the lake, protecting commerce against piracy or, more often, seeking and slaying the troublesome sea serpents wherever they can be found.