Daytrips from basecamp require few essentials--all of which the Isolation HD 19L Backpack from Outdoor Research can carry. With 19L of interior space, the Isolation HD can easily pack a few extra layers, snacks, and a first-aid kit, all while leaving room for your water bottle in the external mesh pocket. The internal pocket will keep your personal items secure, too, so you can focus more on reaching the summit than having to scour the trail on the way back down for your lost item. Once your return and you want to use the pack in town, there's plenty of space for a laptop and a lunch so your one backpack can serve the purpose of two.