We're avid day-hikers around here (Tom logs an average of 1200 trail miles each year) and several of our backpacks were either originally designed as hiking packs or can easily do double-duty as such. Our day hiking backpack options range from the Synapse 19 (great for summer or short day hikes) to The Guide's Pack (with its internal frame sheet and large capacity, it can be used as a minimalist overnight pack).
Clean lines and serious organization.
Volume: 26 liters (1600 cu. in.)
A backpack well suited to hiking, travel, or commuting.
Volume: 19 liters (1160 cu.in.)
One backpack for: Ultralight travel. Day hikes. EDC.
Volume: 25 liters (1526 cu.in.)
Top-loading internal frame backpack for the great outdoors and beyond.
Volume: 31 liters (1900 cu.in.)