A cooling system with a thin walled cooling plate. The system includes an enclosure with a cover that defines an interior space and that has an open side. Temperature sensitive devices are contained in the interior space. A cooling plate closes the open side and includes an inner side with a surface that is substantially flat and that faces into the interior. The cooling plate defines a flow channel adjacent the inner side that is configured to channel a circulating fluid to remove heat from the interior space. The flow channel extends across substantially all of the opening. An outer side of the cooling plate may be anodized to block heat from entering the interior space through the cooling plate.