The giant caiman’s frightening head, as big as a tractor trailer, closed on our aft monitor.

Twenty yards… ten… !

We swerved to starboard, and the creature turned with us, its head rolling sideways as its jaws widened—

Crunch!

The Purussaurus engulfed the dead juvenile sea cow, along with the two whitetip sharks that were feeding upon its gushing remains. The giant croc slowed to swallow its meal, circling its kill zone lest another challenger enter.

Ben laid back in his seat, sweat pouring down his face. “Take over, Zach. Shut down the lasers. Keep us heading west. Ming… I deserve a bonus.”

The Chinese beauty leaned over her console and kissed his forehead.

I engaged the controls and shut down the Valkyries, my eyes catching the air supply gauge as it inched below seven hours.

We were down to five hours and twenty-two minutes when Ming and I heard the faint sound of rushing water over our headphones. Sonar tracked the sound to the west where a channel of current appeared to be rushing inland. The surface above us had no vegetation, the waves far too violent to allow anything to accumulate.

I roused Ben from his sleep. “We found something, a channel running inland. If the river cuts across the plateau it could empty into the northern basin.”

“What happens if it strands us in the shallows and we beach? You want to be the one who gets out and pushes?”

Ming interjected, her tone soothing. “Ben, we have followed the plateau for twenty miles. From the satellite images we know the rise is at least thirty miles wide. Perhaps there is another inlet somewhere, but if we do not begin crossing the plateau soon we will run out of air.”

The pilot nodded. “I’ll take the conn. Zach on sonar. Once we move into the channel, I want you to go active to gauge the depth. If it seems deep enough we’ll give it a shot. If not, we head back and continue the search. Agreed?”

“Agreed.”

Ben took a moment to relieve his bladder using his plastic-bottle urinal. Then, taking over as pilot, he ascended the sub into the channel.

We surfaced into a swiftly moving deluge, driven by ten- to twelve-foot waves that lifted our craft and nearly tossed us over the first curl.

Ben accelerated ahead of the next swell, offering us a glimpse of what lay ahead.

The water was being channeled between two headlands, seven- to ten-story cliffs that jutted out into the lake. The waterway was as wide as an eight-lane highway, but its length and depth were impossible to gauge.

I waited until we were closer to the whitewater entrance before going active on sonar.

The acoustic PING rippled across the channel, its reverberations painting the waterway’s topography. The river swept inland another half-mile before the shallows appeared, where the depths reduced from seven hundred feet to eighty-five feet—certainly deep enough to accommodate our tiny sub.