That settled my shark dilemma. It was not just Antarctica, after all, that had frozen millions of years ago; the oceans surrounding the continent had also incurred a precarious drop in temperature. A river bleeding a warm-water current into coastal waters would have lured many ocean species.

I shuddered to think what else might be down here.

I got an answer as we passed sixteen hundred feet. A thousand shadows materialized all around us in every direction, becoming bulbous eyes and jaws that unhinged, and bizarre fish with needle-sharp teeth, many of which cast bioluminescent lanterns that dangled before their open mouths like bait. These were Vostok’s deepwater creatures, Miocene mutations forced to adapt to the darkness and cold.

But not cold, for the water temperature was fifty-seven degrees and still rising.

As we descended to twenty-two hundred feet, a gray haze began to appear, chasing away Vostok’s denizens of the deep.

At twenty-four hundred feet, the water temperature had risen to sixty-three degrees.

Forty more feet and I saw the first black smoker.

Hydrothermal vents were first discovered in the Pacific Ocean back in 1977. Since then, they had been found in every ocean as well as in certain rift lakes.

Vostok was just such a lake, formed when East Antarctica’s crustal plates had separated, creating a valley that became the waterway’s basin. The geothermal vents were switched on when cold water began seeping into cracks along the forming lake’s floor. Heated by molten rock in the earth’s mantle, the water mixed with oxygen, magnesium, potassium, and other minerals before being forcibly ejected back into the lake. Once this hot mineral soup met Vostok’s cold, oxygen-rich water, it generated hydrogen sulfide, which in turn fueled bacteria—the foundation of the lake’s chemosynthetic food chain.

Avoiding direct contact with the superheated discharges, Ben gave us a tour of the vent field, a petrified forest of volcanic chimneys that spewed billowing dark clouds of mineral-laden water, which spawned a thriving subglacial ecosystem. Piled along the base of these vents was a mosh-pit of life—crustaceans and shrimp, clams and anemone—everything white and twice the size of similar species outside of Vostok. Our sub rocked in eighty-nine-degree water as we passed over miles of vent fields, small fish feeding off the spaghetti-like clusters of tubeworms that grew in acre-size clusters.

“All right, Zach, Ming—we’ve taken a look. What say we move on before this mineral water clogs one of the engine’s intake valves?”

Not waiting for our reply, Ben began our ascent as we continued our trek to the northeast.

We had journeyed another three nautical miles when we discovered another missing cog in Vostok’s thriving ecosystem.

Upon reaching a depth of 420 feet, we discovered strands of what appeared to be kelp dangling across our cockpit glass. The higher we rose, the denser the growth, until we were surrounded by thick strands of algae.