The metallic core of the gas giant Bespin, composed of liquid rethin metal (also called "rethen"), was referred to as the Rethin Sea. During the events of the Trioculus affair, the Imperial forces built a factory barge suspended over this sea to extract metals and tibanna for manufacturing. This factory's operations resulted in the creation of braze (short for "brown haze"), a substance that caused significant atmospheric contamination on Bespin.