My buddy and I began our trip at the Pine River campground near the town of Bayfield. We packed up to Rock Lake stopping at Lake Creek and Emerald Lake on the way. We returned using the Flint Creek trail. The entire trip was 5 days. It was a very nice hike.
We decided to attempt Mt. Oso the second day on the trail and had no beta except the Trails Illustrated map for the Weminuche Wilderness. I studied the map untill my eyes popped out! Obviously the map was not nearly detailed enough to plan a proper attempt, but we had nothing to loose so we tried.
My planed route was actually the same as recomended on this site. Though I made one error, I stayed on the high ridge southeast of Lake Mary Alice planning to stop at the lake to eat granola bars and get much needed water. The map I had was not detailed enough to show that from the rocky ridge the lake was inaccessible (too steep). We had a great view of the proposed route and when I saw the steep rocky slope leading up the southern ridge of the mountain I thought it looked too steep and unstable. My second idea was to hike around the mountain to Lost Lake and climb up the southern slope where it looked to be less steep ( from my poor map). Unfortunately my buddy (Apu) was not game for another attempt (day). The worst part of the attempt was that after retreating back to camp at Rock Lake Mt. Oso was peeking at us from between Peters Peak and the rocky ridge. It was demoralizing. Next time (there will be a next time) I will try from Lost Lake first.