A convertible storage assembly is disclosed with a body with an interior space. In an embodiment, a removable waterproof liner may divide the space into first and second compartments. With a liner in place, the first compartment is accessible through a first removable barrier and is water-retaining due to the liner: and the second compartment is accessible through a second removable barrier. The size of the second compartment may be changed by deforming a flexible liner, or by changing from a first liner to a second liner of different shape.