The mouth, hanging open, reminded Mironov of bear-trap lined with hand-length triangular teeth, each serrated and designed for tearing and cutting flesh. The long powerful body was gray-black with a pale belly. And then there was the fist-sized eye, cold and darker than the surrounding water. The creature seemed to slow momentarily, and Mironov knew it saw them then. It looked in through the glass, saw them, and wanted them.

A single flick of a two-story tall, scythe-like tail, and it vanished again in the stygian darkness.

“Shark.” Was all Dmitry said.

“It’s much worse than that,” Mironov said softly. “It is the father of all sharks – the Carcharodon Megalodon.”

Time seemed to freeze, and Mironov knew he was holding his breath. Through the window there was nothing now but an impenetrable darkness. He strained every sense he had, waiting, and then the Prusalka rang like a bell and half rolled in the water. Both men were jolted in their seats.

“We’re hit.” Dmitry looked everywhere at once.

Mironov quickly checked his screens. His thinking was scrambled and his head ached as it seemed every proximity and warning alarm they had was screaming at them in unison.

Dmitry moved from screen to screen. “No sign. Maybe we are not to its taste.” He shut down the alarms and checked the sonar again, putting it on speaker. There was no sound, no telltale pings that heralded the return of their attacker.

Dmitry nodded. “Time to go.” He powered the vessel away and upwards, heading back the way they had come.

“Where are we going?” Mironov kept his eyes on his screens.

“Anywhere but here,” the Russian declared.

Mironov wiped his brow. “When I was much younger, we sailed through the seal colonies in South Australia. They congregate on rocky outcrops, but when they entered the water to fish, they had to first pass over some deep underwater trenches. They usually learned to stay at its edges, and not venture out over the dark water.” He looked across to Dmitry. “Because that mistake was only ever made once – the deep water was where the big sharks waited. Circling down in the dark, they would come up from the depths so fast the seals never had a chance.”

Dmitry nodded, his face white. “Just keep watch on the sonar – I’m putting it on speaker.”

There was silence for several seconds.

Ping…

The two men froze.

Ping…

Mironov’s hands gripped his armrests.

Ping… ping… ping…

“Chyort voz'mi!” Dmitry’s teeth showed in a frightened rictus. “Coming from below – like for seals.” His arms strained on the wheel, and his lips remained pulled back. He seemed to be willing the submersible to go faster, adding every ounce of his own strength into the engines.

The second impact threw them from their seats again, even though they had braced themselves. Their world turned upside down. Alarms screamed again, and this time something hissed. Metal groaned beneath them.