The park is mostly boreal forest, with a variety of ecosystems ranging from lowland wet areas to alpine tundra. The main tree species are white and black spruce, lodgepole pine, jackpine, subalpine fir, larch, balsam poplar, trembling aspen and white birch. The varied ecosystems resulting from varied altitudes, hot and cold springs, and river influence results in a diversity of vegetation.
The park is home to a variety of wildlife including Dall's sheep, mountain goats, woodland caribou, wolves, black bears, grizzly bears and trumpeter swans.
The climate is cold and highly variable and visitors should be prepared for extremes. July and August are generally warmest with temperatures between 0°C to 30°C, with frost possible at night toward the end of the period. The river begins icing in September.
Parks Canada does charge visitors to Nahanni a fee. Parks Canada employees track your progress throughout the park (utilizing their Park Wardens and river check-in points) and this fee covers the costs of managing the park. For most visitors on a planned canoe trip this fee will be around C$175. 
The park offers whitewater canoeing, kayaking and rafting trips ranging from ten days to three weeks. Make reservations well in advance through the Park Office.
While there are no developed trails, route descriptions are available for a few of the more popular hikes.
Flight-seeing day trips are available by air charter to Virginia Falls. Day visitors to Virginia Falls can enjoy a picnic as well as a short walk to the viewpoint. A longer portage trail, of moderate difficulty, descends to the base of the falls. Allow two hours return for the hike.