For the intrepid, the hike up to Camp Muir gives you a sense of what summiting Mount Rainier might take, and an appreciation for the grueling climb beyond. Even though it's the highest point in the park you can hike without a climbing permit, this isn't a hike to take lightly.
Before starting out, check the road status as unexpected road closures can happen at any time due to snow, flooding, rock falls or other causes. The Mount Rainier National Park Service does a nice job of updating their Facebook page with relevant information, which can be found here.
The trail to Camp Muir starts from Paradise, which is plowed year-round and is the most visited area in Mount Rainier National Park. Take note that parking at Paradise on winter weekends and during the summer can be difficult, so carpool whenever possible. The road between the Nisqually Entrance, Longmire and Paradise takes you past several trailheads and eventually to two parking lots: The Upper Paradise lot at 5,400 feet is for short visits, while the Lower Paradise lot can be used for stays longer than two hours (park here if space is available). Parking is not permitted on the sides of the road. Due to congestion at Paradise, consider using the free weekend Paradise Shuttle instead, which runs from the town of Ashford at the western edge of the park and through the Nisqually Entrance to Longmire and Paradise during the summer weekends, stopping at points of interest along the way.
Take the trail behind the Paradise visitor center on the Skyline Trail, past Glacier Vista and up a switchback. Follow the signs to Pebble Creek and Camp Muir. Be prepared for a variety of conditions, as the route is usually under snow well into August. Begin the route on two miles of paved trail before meandering over rocky trail and subalpine meadows. Get fresh water at Pebble Creek (treat it before drinking), unless you're prepared to melt snow. The trail eventually reaches the Muir Snowfield (which may have snow near-round), and a steep climb ahead. Keep your eyes out for great views of surrounding mountains, like Mount Adams, St. Helens and Hood. Once you see Camp Muir ahead, you have 1,000 feet more to climb. Don't despair! You're almost there. After a rest, make sure to watch your footing on the way down. Use extra caution in poor visibility, and definitely avoid stumbling onto the crevasse-pocked Nisqually Glacier to the right.
Keep in mind that Paradise is popular for backcountry skiing and snowshoeing during the winter months, and park hours change seasonally. Check the hours before you go. Mid-July and August are your best bet to reach Camp Muir, and to experience Mount Rainier at its best; especially the wildflowers. Get up to date wildflower information, here.
Summer weekend lines to get into the park can be long, so follow these tips to avoid crowds.
An entrance fee is required to enter Mount Rainier National Park, though no backcountry or climbing permit is required to enjoy a day hike to Camp Muir.
This is a strenuous trail up to 10,000 feet in elevation, so taking young children is not recommended. Check out other great options within Mount Rainier National Park for a diverse range of trails.