The Trekker backpack by FCS is a large pack. At 35 Liters, it's over twice the size of a normal school pack. The main compartment has a removable wetsuit bag and can be loaded from the top or bottom. In addition there are pockets and organizers everywhere you look including a fleece lined sunglass or IPOD pocket with headphone wire access.There are padded hip protectors with compression straps, super think, dual-density foam shoulder straps, and a rigid back support system for comfort. Lockable zippers, lined wet zones with drainage holes, and a water resistant base add to this first class pack.