A flexible storage bag comprising at least one sheet of flexible sheet material assembled to form a semi-enclosed container having an opening and a closure means for sealing said opening to convert said semi-enclosed container to a closed container, said opening having a periphery, wherein said closure means comprises a piece of material forming substantially all of said periphery, said piece of material having a first side facing inwardly toward said opening and a second side facing outwardly of said opening, said first side exhibiting an adhesion peel force after activation by a user which is greater than an adhesion peel force exhibited prior to activation by a user, such that said first side is adherable to any opposing surface, said closure being a selectively activatable adhesive structure and comprising a three-dimensional, deformable material comprising an adhesive protected from external contact by the three-dimensional surface topography, and which is convertible to a substantially two-dimensional sheet material upon activation by a user to expose an adhesive layer to contact with an opposing surface of said semi-enclosed container across said opening.