The central feature of the park is the South Nahanni River which runs the length of the park, beginning near Moose Ponds and ending when it meets the Liard River near Nahanni Butte. The South Nahanni is a rare example of an antecedent river. The mountains rose slowly enough, and the river was powerful enough that the river maintained its course over its history, meaning it has the same path today as it did before the mountains rose. As the river was meandering, the canyons it carved also meander. Most visitors only visit the portions from Virginia Falls ("Nailicho") down.