Complex sentence: The rapids are caused by a descent in the elevation of the riverbed, and are considered by locals to be the most dangerous on the Delaware River, though the actual difficulty of navigating this stretch of the river is greatly exaggerated.
Split into simpler sentences: The rapids are caused by a descent in the elevation of the riverbed. These rapids are considered by locals to be the most dangerous on the Delaware River, though the actual difficulty of navigating this stretch of the river is greatly exaggerated.