This unit is known for spectacular views of the Alaska Range, pristine conditions and very little use, but access to the unit and travel within it are extremely difficult. This is the start of the western wilderness of the park and prior experience with cross-country hiking and major glacier river crossings is strongly recommended.
This part of the park is best to access in late August and early September when the fall colors are peaking and the river levels are down.
There is no road access to this Unit. Access is from Unit 15, leaving the Park Road about 0.25 miles east of the Wonder Lake Campground and hiking down the McKinley Bar Trail to the McKinley River. At that point there is no established route to the south side of the McKinley River where Unit 21 starts. See Units 20, 14 and 15 for further information on crossing the McKinley River.
This area is best for people who are doing hikes of 4 nights or longer and want to feel like they are in a remote part of the Alaska Range. Due to the challenges of getting into Unit 21, it is not recommended for backpacking trips of 3 nights or less.
To access this area, most hikers follow the McKinley River bar downstream to the Muddy River. There is an area informally called “the narrows” about 3 miles west of the McKinley River Bar Trail that can be challenging to get around as the river flows in fewer channels and tends to bank up against the north side. The McKinley River changes its course throughout the summer so the Backcountry Information Center will not necessarily know the best way to get around the Narrows.
Clearwater Creek lives up to its name, with crystal clear water, but it also can be very difficult to cross when it is a single channel. The best crossings are near the McKinley River Bar where its grade drops; the creek becomes more difficult to cross when you go more than a mile upstream. Clearwater Creek is a poor travel corridor on foot, with few braids, swift water and rapids.