Farther out still, I saw the dark silhouette of a rise.

Ben and Ming were still arguing in my headphones, distracting my thoughts. “Enough,” I yelled, silencing the voices in my ears. “Ben, I thought the plateau that divides the lake’s northern and southern basin was underwater.”

“Depth is seven hundred feet, according to Vostok Command. Why?”

“Because there’s a ridge out there preventing us from entering the northern basin, and it’s definitely not submerged.”

My two shipmates located their binoculars and panned the northern horizon.

Ming didn’t seem too surprised. “At least three nations studying Vostok claim the lake has islands and tides. Perhaps these radar scans were completed at low tide and confused the partially submerged ridge for islands.”

Ben angrily shoved his binoculars back in their pouch. “Maybe Vostok does have tides, or maybe somebody just screwed up. If a high tide is coming, it’d better get here soon. Otherwise we have about nine and a half hours to figure out how to cross a land bridge in a submersible.”

“There’s something else,” I said. “The external air pressure has dropped again, this time from thirty-nine hundred psi to just over four hundred. That’s a massive pressure differential.”

Ming theorized. “The geothermal vents heated the water. The warmth melted the ice, which carved out the bottom of the ice sheet, creating more air space. That space filled with compressed oxygen and nitrogen particles, which are perpetually being squeezed to the bottom of the glacier. It is this atmosphere that is counteracting Vostok’s external pressure.”

“That doesn’t explain the magnetic interference that’s scrambling your cameras. Ben, as much as I’d like to believe in the tides, I think you’d better take us deep. Maybe we can find an underwater passage that leads into the northern basin.”

The Barracuda slipped beneath the algae mat and descended.

Dancing in and out of our exterior lights was bio-diversity on a scale I had never seen before. There was the kelp forest—a million inverted olive-brown tentacles swaying with the current. Then there were the kelp-feeders—anchovies and mollusks, along with countless other dark creatures. Finally, there were the packs of carnivore fish, their presence attracting a few rogue predators.

Perhaps it was to keep Ming on his good side, but Ben made a special effort to maneuver the sub so as not to disturb the wildlife. At one point he even diverted from our descent so that Ming could collect samples of kelp and several anchovies using a vacuum tube.

Having acquired living specimens seemed to lighten Dr. Liao’s soured demeanor.

It took Ben twenty minutes to dive beyond the olive-brown tentacles of algae into open water.

For a long moment we hovered, gazing at the abyss. Particles of brown soot and debris floated past our lights like dark, mesmerizing snowflakes. My eyelids grew heavy. I yearned for sleep.