In its upper reaches, the Lackawanna River is highly rocky and flows over cobbles. It has virtually continuous whitewater. There are also a few strainers within this reach of the river, due to its small size. Ledges become more common downstream of Forest City and there is one "distinctly high and nasty" ledge near Simpson. Downstream of Carbondale, the river becomes quieter, though there are still some ledges. A few riffles disrupt the otherwise smooth reach between Interstate 81 and Moosic, though there are many ledges at the latter location. In Scranton, the river flows between stone and concrete retaining walls, as well as high banks of slag. In general, riffles and pools on the river form a "watery stairway". The pools can be as short as a few hundred feet or as long as several thousand feet, with larger ones mainly correlating to broad floodplains. Rapids mainly occur in reaches such as Panther Bluff (in Fell Township), the Winson area (in Archbald and Jessup), near Cliff Street (in Scranton), and at the Moosic anticline (in Old Forge).