Abstract: A knapsack to be carried on a person's back comprising a storage compartment and a carrying unit. The storage compartment comprises a bottom wall, a back wall facing the person, a front wall and side wall portions adjacent the back wall. The walls of the storage compartment being substantially rigid and it comprises one or more openings. The carrying unit is releasably attached to the back wall, and comprises carrying straps and a collapsible rucksack which is collapsed when the carrying unit is attached to the storage compartment and may be expanded into a rucksack shape when the carrying unit is detached from the storage compartment.