From Fort Smith , Highway 5 continues through town and loops back south into Alberta  (just beyond town limits). The border is also the northern boundary of Wood Buffalo National Park, the second largest national park in the world (the largest is in Greenland).
Throughout this 45,000-square-kilometer (17,400-square-mile) chunk of boreal forest, boreal plains, shallow lakes, and bogs flow two major rivers—the Peace and Athabasca. These drain into Lake Claire, forming one of the world’s largest freshwater deltas.
The Peace-Athabasca Delta is a mass of confusing channels, shallow lakes, and sedge meadows, surrounded by a wetland that is a prime wintering range for bison, rich in waterfowl, and home to beavers, muskrats, moose, lynx, wolves, and black bears. From the delta, the Slave River, which forms the park’s eastern boundary, flows north into Great Slave Lake.
Probably best known for being the last natural nesting habitat of the rare whooping crane, the park is also home to the world’s largest free-roaming herd of bison. It has extensive salt plains and North America’s finest example of gypsum karst topography—a phenomenon created by underground water activity.
For all of these reasons, and as an intact example of the boreal forest that once circled the entire Northern Hemisphere, Wood Buffalo National Park was declared a UNESCO World Heritage Site in December 1983.
The expansive Salt Plains in the northeast of the park are one of Wood Buffalo’s dominant natural features. Underground water flows through deposits of salt left behind by an ancient saltwater ocean, emerging in the form of salt springs. Large white mounds form at their source, and where the water has evaporated the ground is covered in a fine layer of salt.
The best place to view this phenomenon is from the Salt Plains Overlook, 35 kilometers (22 miles) west of Fort Smith , then 11 kilometers (6.8 miles) south on Parson’s Lake Road. The panoramic view of the plains is spectacular from this spot, but it’s worth taking the one-kilometer (0.6-mile) trail to the bottom of the hill.
In the same vicinity, a bedrock of gypsum karst underlies much of the park. Gypsum is a soft, white rock that slowly dissolves in water. Underground water here has created large cavities beneath this fragile mantle. This type of terrain is known as karst, and this area is the best example of karst terrain in North America. As the bedrock continues to dissolve, the underground caves enlarge, eventually collapsing under their own weight, forming large depressions known as sinkholes. The thousands of sinkholes here vary in size from three meters (10 feet) to 100 meters (330 feet) across. The most accessible large sinkhole is behind the Angus Fire Tower , 150 kilometers (93 miles) west of Fort Smith.
The Peace-Athabasca Delta is in a remote part of this remote park and is rarely visited. Getting to the delta requires some planning because no roads access the area. The most popular visitor destination on the delta is Sweetgrass Station, located 12 kilometers (7.5 miles) south of the Peace River. The site is on the edge of a vast meadow that extends around the north and west shore of Lake Claire, providing a summer range for most of the park’s bison.
A cabin with bunks and a woodstove is available for visitors to the area at no charge, although reservations at the park information center are required. The cabin is an excellent base for exploring the meadows around Lake Claire and viewing the abundant wildlife. From Fort Smith, Northwestern Air (867/872-2216, www.nwal.ca ), charges around $500 each way to fly two people and their gear between Fort Smith and Sweetgrass Station.
The Visitor Reception Centre (126 McDougal Rd., Fort Smith, 867/872-7900, Mon.–Fri. 9 a.m.–5 p.m. plus summer weekends 1–5 p.m.) offers trail information, a short slideshow, and an exhibit room. Another park office (780/697-3662), open similar hours, is in Fort Chipewyan.
Within the park itself, the only developed facilities are at Pine Lake, 60 kilometers (37 miles) south of Fort Smith . The lake has a campground ($15.70 per night) with pit toilets, covered kitchen shelters, and firewood ($6.80 per bundle). On a spit of land jutting into the lake beyond the campground is a picnic area with bug-proof shelters. The park staff presents a summer interpretive program at various locations; check the schedule at the park information center or on the campground notice board.