Abstract: A thermal divider system for an insulated container is provided for thermal regulation and defining a plurality of sub compartments for the insulated container. The thermal divider system includes a rigid insert formed of a thermal (hot/cold) material. The rigid insert is engageable with at least one slot defined on an interior sidewall of the insulated container to avoid shifting of food product contents and other thermally sensitive materials carried in the insulated container. In some embodiments, the rigid insert includes a freezable divider panel that preserves cold temperatures inside a recreational cooler. Other embodiments may include a heat retaining pack that preserves warm temperatures within the insulated container. The invention here eliminates the use of ice and free moving cold packs to keep recreational coolers at cold temperatures. The system may be provided to adapt an insulated container with a removable sidewall carrying the at least one slot.