In a little while their heartbeats slowed and Alex allowed them to return to a walking pace. But regardless of the team’s comfort level he had to order all lights be switched off. Batteries were becoming a prized possession and Silex had already been caught trying to buy Matt’s spares. They could never navigate their way back to the surface in the dark.

Once their eyes grew accustomed to the strange blue glow it was quite comforting to have a 360-degree light source instead of relying on narrow beams. After a while it was Matt who voiced what they could all sense. “It’s getting even lighter.” He was right; the dim blue gloom was turning to an evening-like twilight.

What they now entered could not be called a cavern, or a cave, cathedral or any of the other descriptions applied by cavers and geologists to underground openings or pockets. It could only be described as a world.

“Pellucidar is but a realm of your imagination—nothing more.” Matt had been the first to speak and break the sense of awe at what they were seeing.

“Maybe Edgar Rice Burroughs knew more than he was given credit for,” said Aimee in a slightly hushed voice.

Matt went to rush forward but Alex held up his hand, flat and open-fingered to indicate to Matt that he hold his position. Alex tried to reach out and sense danger but his consciousness was overwhelmed by the massive life forces emanating from the realm before them.

They stood at the mouth of the cave on the curve of a black beach, where the stream emptied into a vast dark ocean. The colossal hollow’s roof and walls were lit with an abundance of the eerie bioluminescent light, making it a permanent twilight. Huge chandeliers of lichens and primitive mosses hung from the ceiling hundreds of feet over their heads and draped the walls like ragged sackcloth. The walls they could see in the near distance were cliffs that had dozens of openings just like the one they had exited from, and the horizon, even though they were in semi-gloom, could not be seen. There was evidence of old rock falls but mainly the slick walls were smooth and draped in mosses, lichens and primitive-looking plants that resembled slime moulds more than any earthly flora. For the most part they were white or translucent, but now and then one would be blood red or cobalt blue, indicating it had tapped into some mineral vein and was converting the rich minerals for its own use.

The underground sea itself was not a dead sheet of glass, but alive with small ripples that appeared on the surface, indicating life was very busy beneath its surface.

Matt turned to Monica. “How can this world exist down here? It’s unbelievable. Looks like it’s been here forever.”