But the darkness wasn't endless.
For a full half-hour they forged at low speed against the flow of the river, sometimes with the walls in sight and sometimes when even the ceiling receded out of view. But eventually the cavern narrowed down into something of a bottleneck, where a dark shingle beach rose inches out of the water. And to one side of the beach, where the wall was split with a massive crack, there the water had a glowing, milky sheen to it, as if lit by some strange submarine fire.
Nathan recognized that soft but somehow unwelcoming glow well enough. 'Beyond that crack in the wall there,' he said to Trask, 'stands the Gate.' And to prove it, if only to himself, he conjured a Mobius door - which at once warped and collapsed in upon itself. As it had been in Perchorsk, so it was here in the bowels of the earth: the close proximity of the Gate interfered with the space-time matrix, and with the Mobius Continuum, of course.
After beaching the dinghies, two of the cavers pulled on vests and fins and set off at once into the water. Swimming to the crack in the wall, they upended and disappeared into the glowing depths. Behind them, they trailed a luminous nylon line made fast to a knob of rock projecting from the wall of the cave. In only a minute or two they were back and signalling that Nathan, Trask and Chung should enter the water. In wetsuits and wearing aqualungs, the three
took up positions between their guides and hauled themselves hand over hand along the line. So they came to the cavern of the Gate. There, on a dry ledge, they stripped down, and one of the cavers took the smallest of the wetsuits and a lung back through the sump for Anna Marie. Assisted by the caver spokesman and his 2 I/C, she was the last to come through.
Before entering the water with her, Anna Marie's escorts partially deflated the sausage transporter and made it fast to the end of the line. As for the dinghies, they were simply cast off and left to drift downstream. And finally all seven of the party stood in the cavern of the Gate.
The cavers had been here before; however strange, this was nothing new to them. But while they hauled on the line and recovered the sausage, Nathan's small arsenal and various items of dry clothing, the other four stood gazing all about, plainly in awe of the place. Mainly they looked at the Gate - or rather, they shielded their eyes from its glare.
The Gate. It looked nothing like a gate in the common meaning of the word. Instead, it was the very duplicate of that gigantic sphere of alien white light down in the core at Perchorsk. Except here, the bulk of its mass seemed lodged in the low ceiling, or grown there like a massive blister of cold fire.
The way home,' Nathan said simply, but his words were a sigh, perhaps even a prayer.
Looking at him Trask thought, And this time there really is only one way out.
If Nathan heard him, he made no answer ...
PART TWO
Sunside/Starside
I
Starside
Staring with squinting eyes all about the cavern of the Gate, Trask thought, We might already be in another world! And those (he shrank from the shapes of several dripstone anomalies) must be its inhabitants.