A watercraft includes a lower hull, a deck having an opening provided therein, a storage plate, and a storage space defined by a portion of the lower hull, a portion of the deck, and the storage plate. The storage plate has at least one folding line such that the storage plate can be inserted through the opening in the deck when the storage plate is folded along the at least one folding line, and such that the storage plate can be unfolded and installed inside of the hull to define the storage space.