"Steve, talk to me!"

Cold sweat soaked his body. He finally managed to speak. "I got startled -- collided with the canyon wall -- "

"Is there any damage?"

He looked out the dome. "I can't tell. I think I bumped against the cliff with the forward sonar unit."

"Can you still maneuver?"

He tried the joysticks, nudging the craft to port. "Yes. Yes." released a deep breath. "I think I'm okay. Something swam right past my dome. Got me rattled."

"Something?"

"It went by so fast! Just this streak -- like a snake whipping by."

"Did it look like a fish's head on an eel's body?"

"Yes. Yes, that's what I saw."

"Then it was an eelpout. Thermarces cerberus."

Cerberus, thought Ahearn with a shudder. The three-headed dog guarding the gates of hell.

"It's attracted to the heat and sulfur," said Helen. "You'll see more of them as you get closer to the vent."

If you say so. Ahearn knew next to nothing about marine biology.

The creatures now drifting past his acrylic head dome were merely objects of curiosity to him, living signposts pointing the to his goal.

With both hands steady at the controls now, he maneuvered Deep Flight IV deeper into the abyss.

Two thousand meters. Three thousand.

What if he had damaged the hull?

Four thousand meters, the crushing pressure of water increasing linearly as he descended. The water was blacker now, colored by plumes of sulfur from the vent below. The wing lights scarcely penetrated that thick mineral suspension. Blinded by the swirls of sediment, he maneuvered out of the sulfur-tinged water, and his improved. He was descending to one side of the hydrothermal vent, out of the plume of magma-heated water, yet the external temperature continued to climb.

One hundred twenty degrees Fahrenheit.