A divider device for dividing an interior chamber of a cooler into a plurality of separate chambers and preventing fluid flow between the plurality of chambers. The divider device has a dividing wall that is insertable into the interior chamber of the cooler. A waterproof seal is positioned around the outer surfaces of the dividing wall. The seal is inflatable by a pump that is part of the divider device such that the seal is urged into contact with walls of the interior chamber to form a fluid-tight seal that prevents fluid flow from a first side of the dividing wall to a second side of the dividing wall.