The Crook River is one of the two main tributaries to the River Sphinx in Osirion. It begins in the foothills of the Barrier Wall mountains in southwestern Osirion and drains the entire Brazen Frontier region, flowing at a steady but sluggish pace in a generally easterly direction for approximately 200 miles before joining the Asp to form the Sphinx. The lands at either side of the Crook are flat flood plains, heavily farmed near the city of Ipeq. Elsewhere, the plains are mostly marches and dangerous because of the crocodiles and hippopotamuses.
The easy crossings are only two: the Shallows of Ipeq and the Khopesh Span bridge to the east. At Oxjaw Falls, to the west, travelers on foot may also try a treacherous pass across the river. The only other way to cross the river is to find fisher folk willing to ferry the travelers at some of the infrequent river settlements. Upriver the traders use skiffs capable to travel through the stretches of rapids which are used as ideal ambush points for gnoll and other raiders.