Regan pondered this for a while and then reasoned that there was a swift current, swifter in the middle even than his rocket propulsion at the side of the channel. He worked himself out toward the center, then switched off his rocket, experimentally. By watching the rock side of the passage, he was able to gauge that he was moving much faster. The watching, however, had a hypnotic effect on him and Regan felt himself dozing off. He tried to fight it but reasoned finally that there wasn't much point. So he turned off his headlamp and let himself go to sleep. He felt weird when he woke up. He was hot and sweating. He remembered instantly where he was. It was no comfort to him. He felt entirely hopeless, even more so than if he'd been marooned in space. At least there was traffic out there. Here there was just himself, with a wooden cask up ahead and nightmarish fish somewhere behind. He also felt weak. Spacesuits come equipped with water, of course, if they're the repair variety, and Regan drank sparingly through the tube at the base of his faceplate. But his suit carried no rations, so he tried to ignore his hunger. He drowsed again and switched off his headlamp. This became a pattern for him--a semi-conscious nightmare of smooth, eerie motion, punctuated with sips at his water supply and hopeless watching through the faceplate, blinking away the sweat. Regan talked to himself, he said, and sometimes sang, to keep himself sane in the silence and loneliness. It probably helped, although some of his talk was pretty idiotic. It was after one of his dozes--whose duration he had no way of measuring even by his thirst and hunger, which were constant--that he awoke to something new. Automatically he switched on his headlamp, then switched it off again, realizing what the newness was. The passage he was being washed through was no longer dark; there was a radiance in the water now. Regan twisted himself around to see what the light came from. Up ahead, apparently. As it got stronger, his eyes began to ache. It was a gorgeous ache, Regan said, and he stared ahead almost hypnotized. He made an effort and focused on the walls of the passageway he was being thrust along. They were white with streaks of black in them--like marble, but without marble's glossy hardness. He could see all parts of the tunnel now; it was roughly circular and had narrowed to a diameter of about two hundred feet. Regan could only suppose that he was nearing the surface--that he'd been sweeping through some U-shaped fissure--and he adjusted himself kinesthetically to the theory that he was now traveling up instead of down. This took a lot of doing and occupied his mind.