Expandable backpack

A backpack comprising, in combination:

• a main panel, generally rectangular in shape, having a top, a bottom, two side edges, a front side, and a rear side;
• a pair of primary storage compartments, each having a front panel, a rear panel, two side panels, a top panel, and a bottom panel, with these panels being fixedly attached to one another such that they form a storage compartment with an interior space, and having apertures formed in or near the top for allowing access to said compartment, and each storage compartment being fixedly attached near to the outward edge of the front of said main panel of the backpack, and each storage compartment being releasably attached to the inward side of the other storage compartment;
• a releasable closure extending vertically along the central dorsal length of said backpack, adjoining and releasably connecting the two said primary storage compartments such that when said releasable closure is closed these primary storage compartments are held fast, each to the other, having their back panels positioned in an approximately parallel orientation to said main panel of the backpack, and such that when said releasable closure is opened, said primary storage compartments are able to hinge and rotate about the axis of their line of attachment to the backpack such that their back panels are thence approximately perpendicular to said main panel of the backpack, and a supplemental storage area is exposed;
• a pair of shoulder straps fixedly attached to said backpack proximal top rear side of said main panel, with the other end being fixedly attached proximal bottom rear side of said main panel, to allow said backpack to be carried on the back of a wearer.