A container with a barrier insert is disclosed. The container comprises: a lid including a top surface, a lid side wall extending from the top surface, and a lid interior compartment; a base including a bottom surface, and a base side wall extending from the bottom surface and including an upper edge; and an insert adapted to fit within the interior compartment of the lid such that the insert is in contact with the upper edge of the base side wall to enhance barrier performance of the container when the container is a closed configuration. When desired, the container may include at least one locking structure such as a protrusion structure to secure the lid to the base when the container is closed. Various shapes of the insert may be used, such as an inverted "U" shape, a step, a stepped hybrid, and a standard "U" shape.