Classicly

Conroy, working his way down the tube, suddenly felt emptiness as he lowered one foot. He had come to the end of the vertical tube. Twisting himself upright, he dropped the remaining six feet into the huge arterial tube that ran horizontally into this sector of the ship. The escape hatch shouldn't be too far from here. The pipes needed cleaning after the irrigation period was over and the tubes had entrance ports for the purpose. Conroy strode down the tube in total darkness, keeping one hand against the side. He opened the hatch and found himself in one of the pumping rooms.