Gannon had thought the old Aussie was a little off his rocker until he dived down with him and saw the amazing subway-like network of corridors and caves with his own eyes. Several channels were almost a mile in length and went down hundreds of feet in depth. Every day for two weeks they had explored and mapped the cave network with guide ropes and radiolocation transmitters.

From behind his seat, Gannon produced a cardboard tube and tipped out the rolled-up laminated map that he and the professor had made of the cave system.

Then he clicked on a flashlight and uncapped a Sharpie marker.

It was almost 3:30 on his wrist dive computer when he finally managed to get his game plan sussed out and all his equipment and the money bag lowered on ropes down to the water.

He had just climbed down himself and was about to get into his tanks when he realized he had forgotten something after all.

“If it’s not one thing, it’s another,” he mumbled to the darkness as he scurried back up the rope and rock in his bare feet.

He went to the Gator and lifted up the green cloth fishing rod bag he’d left in the foot well. He couldn’t strap the small cloth bag to his back because of the tanks, so he decided to tape it to his lower right leg with a few wraps of black vinyl electrical tape he’d brought along.

Two minutes later, Gannon was finally back down in the warm water of the blue hole completely geared up.

Here goes nothing, he thought, as he finally untied the heavy money-filled bag and let its weight take him down.

Most of the top part of the hole was like the bowl of a giant wineglass. But at seventy feet, its bottom tapered, and three corridor-like passageways opened up, two to the west and one to the east.

Gannon took the eastern passageway that went another thirty feet down in an angled sort of corridor that was like a steep stairwell with no stairs. At the bottom of the stairwell was a short corridor-like passage that went in two directions, east and west.

Remembering the directions he’d memorized, Gannon went to the left, east, and passed two more branches: one to the left and one to the right, and then a third on the left that he took. A hundred feet in on a level plane, the walls and ceiling of the hotel corridor–like passage began to close narrower and narrower to that of a barely diver-wide pipe.

Just when it looked like it was going to dead-end, the pipe suddenly opened up into a huge rectilinear chamber that rose up thirty or so feet.

Gannon pulled himself in through the manhole-sized opening and swung his light up at the stalactites. The professor had dubbed the chamber “the cathedral” because of its height.

Along the high wall to his right, about twenty feet up, he stopped the light where a horizontal lip of rock jutted out.