Arc'teryx Khamsin 70

Have used this pack and numerous alpine climbing and mountaineering trips.  Very durable, fabric that held up to all the abuse of 6 weeks in the North Cascades and Picket Range. Handles loads of 50+ pounds, no worries, and then stripes down and compresses for a summit push with ease. 

The Arc'teryx ice axe holds are a nice touch allowing you to remove you ice axe without taking off your pack. Excellent. Has gear loops on hip belt so there is no need for a rack acorss your shoulder or to have a lot of gear on your harness. 

The pack stayed dry through rain and snow storms. I had no need for dry sacks when I used this bag.  Bushwacking through the Picket Range and sliding down hillsides or scree fields caused no abrasions or tears.

Side access zipper great feature to pull gear/clothes out quickly with out un packing. or get you climbing parener to pull it out with taking your pack off.  The many features of this pack allow for endless modification based on your needs.  

Best uses: Alpine climning, Mountaineering, Ice climbing, or any other time when you need a durabel water resistant pack that has the features you need to reach the summit.