The hike around Oregon's Three Sisters is rivaled only by the Timberline Trail around Mount Hood as a premiere backpacking trip in Oregon. The Three Sisters are the third, fourth, and fifth tallest mountains in the state, and each mountain exceeds 10,000 feet in elevation. The mountains include 15 named glaciers, almost half of Oregon’s 35 named glaciers. The three volcanic peaks create a diverse ecosystem of glacial-cut valleys, alpine tundra, lakes, volcanic lava fields, and dense forest that all beg to be explored. There are many ways to accomplish this hike, but the most popular is to hike counterclockwise starting from Devils Lake Campground at the south end, including a summit of South Sister (a 10,358-foot walk-up) if you have the time. All three mountains originated in different geological situations, and the composition of each mountain varies greatly. South Sister is still active, having erupted only 2,000 years ago, while Middle Sister is dormant and North Sister is extinct.
Beginning from Devils Lake, start by climbing on the South Sister summit trail until the first four-way intersection with the Moraine Lake Trail. Turn right and hike past Moraine Lake, taking in the wonderful reflection of South Sister off of its surface. Continue onward and turn left at the Green Lakes junction and continue north along the flank of South Sister.
If you have a good GPS unit, map, and navigation skills, there exists a way to connect the Green Lakes Trail to excellent off-trail camping and to reconnect at Camp Lake to rejoin the main loop. Follow the terrain carefully along the shelf extending north from the Green Lakes Trail once it begins to lose elevation on the far side of the pass. You will cross several creek beds, which may be dry depending on the time of year and rainfall. Once you come to a cliff, enjoy the views and then turn left to climb up toward Chamber Lakes. There are several permanent snowfields that make good water sources and clearings that make excellent camping. Drop down on the far side of the highest spur and make your way down to Camp Lake and take the trail back down to the Green Lakes Trail. Turn left at the intersection to make your way to Scott Pass and the Matthieu Lakes area.
This is where the trail turns back south along the Pacific Crest Trail and through dramatic volcanic lava beds. Soak in the diverse colors of the snow, sky, and red volcanic rock as you pass by North, Middle, and then toward South Sister. If you have the energy, Collier Cone makes a great viewpoint, but there are better to come in case your legs try to argue with you. Take care when passing through the Obsidian Zone, where permits for passing through are required for any of the trails except the Pacific Crest Trail.
Continue on the PCT until you reach the Le Conte Crater Trail to your left, and make sure you are full on water before taking the turn because there will be few water sources until the lake halfway up summit of South Sister the following morning. There are many fields to choose from for camping if you are trying to summit South Sister the next day; otherwise you will soon reach the four-way intersection on the first day.
If you do attempt to summit, make sure you leave as early as possible to beat the crowds coming up from Devils Lake and to catch the sunrise from the mountain itself. With good weather, the view from South Sister north will be something you’ll never forget, with a string of mountains before you including Middle Sister, North Sister, Three Fingered Jack, Mount Jefferson, Mount Washington, and on a very clear day you might be lucky enough to see Mount Hood.
Make your way safely back down the volcanic rock toward the trailhead, where hordes of people will surely be passing you on their way up. Great views of the lava fields from above, Mount Bachelor, and Broken Top will keep you entertained most of the way down until you enter the dense forest below the intersection. Follow it back to your car and get a well deserved meal in Bend before you head home.