I have hiked the whole thing in one day and camped to split the trek into two. For me, the best way to experience this mountain is to camp. Climbing up the South Sister is just too much to rush in one day. That's because there is just so much to take in. You travel across many different forests, all which are at different altitudes. Though if all you have to spare is one day, and want to summit one of the prettiest and easiest cascade peaks, then it makes sense to rush it. The first thing you will notice is that this is a very busy trail. On a busy summer weekend, this trial looks like a trial of ants up an ant mound. The reason is that it's the third tallest peak in Oregon and can be hiked without climbing gear. The first section of this trail is steep and runs through a beautiful conifer forest. After you get to the top of this section, you will enter an alpine desert. Then after walking through the last bit of trees, it suddenly dawns on you that you have a long way to go. The view of the mountain from here is outstanding. At the end of the little alpine desert, you will see a few lakes that make for a great place to backcountry camp. If this is your first time camping in the backcountry follow the Leave No Trace link at the end of this review to keep yourself on track. From the base of the mountain, it starts to get steep as you might imagine. It stays steep the whole way up after this point. Eventually, after climbing up some granite-like rocks you will reach a false summit. I have been deceived by this summit a few times. Just know that if you see the top and it's not made of red cinder, you're not at the top. Once you reach the false summit, you will reach a little lake. If you have water purification, this could be a great stop to refuel on water. Don't be tempted to drink this water without filtering it first. You may think it looks majestic and untouched, but there are a lot of people who hike this trail. The last stretch of this trail is the most difficult by far. It gets steeper and the trail can be hard to see. The cinder at the top will slide backward, and you will feel like your sliding back one step for every two that you take. Once you reach the top, it will be obvious. You will see a giant crater at the top with a blue glacier lake in the center. The trail travels along the crater and you will see one of the most rewarding views in Central Oregon. The other mountains will appear to be fake like you're in some sort of postcard. But it's real, you can see the other cascade volcanoes all in a line and even see some mountains into Washington. Overall this is one of the most rewarding experiences. Just remember to respect the land, bring plenty of food, water, fill out a permit at the trailhead and pay for your parking to avoid a ticket and you will have a great time.
Here is a link for the best "Leave No Trace" practices
https://lnt.org/learn/7-principles
Here is a link for the trail map and elevation details https://www.alltrails.com/trail/us/oregon/south-sister-summit
Here is a link to the land management agency that manages this trail
https://www.fs.usda.gov/recarea/deschutes/recarea/?recid=39000 read more