A foldable storage case comprises a one-piece, waterproof container. The container comprises a body, a bottom, and a cover, where the body, the bottom, and the cover form an interior space therebetween. The body comprises a plurality of body panels, the bottom comprises a plurality of bottom panels, and the cover comprises a plurality of cover panels. A plurality of removable fasteners is used to fasten together the body panels and the bottom panels. Further, each cover panel includes a projection adapted to be received by a receiving area of at least one of the body panels. When the cover is folded such that two or more projections are disposed adjacent each other within the receiving area, the projections and the receiving area interfere with each other, detachably securing the cover panels in place.