Visibility was bad when the Wadatsumi slipped below the surface the next day, with Tadokoro and Yukinaga aboard. It plunged into the jaws of a vast black watery void, and at 3,000 feet darkness swallowed it up completely. The force of the water coming to bear upon a portion of metal no larger than the palm of a hand was more than 100 tons. The Wadatsumi continued its dive smoothly at a speed of three knots an hour into that freezing hell of crushing pressure, like a specimen sealed in blue glass. The interior of the gondola became cold. Moisture condensed in drops upon the inner walls.
“It would be good to put on your jackets,” said Onodera.
The control board glowed with a green, firefly-like light. At 5,000 feet Onodera turned on the searchlight, and the water seemed to envelop the Wadatsumi like a gray-blue fog. From time to time, strange creatures of the deep floated up into the spotlight and then swam casually away without showing the least interest in the odd invader.
“Ten thousand feet,” said Onodera, his eyes on the water-pressure gauge. “To the left there . . . the trench slope begins. The distance is eight miles. The slope angle is twenty-five degrees. According to the charts, it should be much steeper.”
The temperature continued to drop. Yukinaga unobtrusively pulled his jacket collar tighter about him. The dehumidifier had begun to take effect. The drops of moisture on the walls and the pipes had disappeared. The inside of the gondola had the hush of a graveyard at dusk. The submarine seemed to Yukinaga like a metal coffin drawn ever deeper into the terrible pressure of the abyss.
Fifteen thousand feet. Professor Yukinaga felt his skin prickle at the thought of the water crowding against the outside of the metal wall a bare twenty inches from his shoulder. He heard a faint crackling noise, and he looked furtively about him.
“Everything’s in good shape,” said Onodera, noticing Yukinaga’s concern. “The instruments contract and pull at their fittings when the temperature drops. Should I turn on the heater?”
“No . . .” said Tadokoro. “We’ll soon be at the bottom?”
“We’re at 17,200 feet,” said Onodera, looking up at the pres sure gauge. “The bottom should be . . .”
There was a loud ping as a downward sound wave gave back an immediate echo.
“. . . 5,850 feet farther.”
Only rarely now did any living thing pass through the search light beam. Sometimes a small jellyfish or shellfish, immune to the terrible pressure, would flash by. When Onodera turned off the searchlight, however, living creatures, like scattered stars, shone with blue-white phosphorescence in the pitch-black void. The water temperature fell to 1.8 degrees Centigrade. One hour and forty-two minutes had passed since they had left the surface behind.
“Twenty-two thousand feet ...”
“That there!” exclaimed Yukinaga, a quaver to his voice. “Is it a ray?”
Outside the left window, a creature like a huge curtain was flapping its way slowly through the searchlight beam.
“Surely,” said Tadokoro, his voice hoarse, “something that big couldn’t be a living thing.”
The creature, caught in the outer circle of light, took a good five or six seconds to pass by. It seemed to be more than 100 feet in length.
“Could we try to track it with the sonar?” asked Yukinaga.
“It’s already way above us,” answered Onodera. “We’ll soon be at the bottom.”
Suddenly there was a loud thump as the submarine took a shocking blow upon its side. The Wadatsumi shuddered, and its nose twisted sharply to the left more than twenty degrees, then thirty degrees back to the right.
“What is it?” Yukinaga asked, his voice harsh. “An accident?”
“No,” answered Onodera calmly. “It seems like it was an undersea tidal current.”
“At a spot this deep?” asked Tadokoro. “A current that strong? How’s that?”
“I don’t know,” answered Onodera. “Sometimes we run into them. But I’ve never hit one that strong before.”
“There’s the bottom,” said Yukinaga, his voice like a sigh.
Directly below them two mustard-colored circles seemed to loom dimly, the targets of the two powerful searchlights pointing straight down from the front and rear of the submarine. Gradually they got brighter, their outlines growing quite distinct. At several points doughnut-shaped clouds of mud whirled up, rising as they broadened, stirred by released ballast. The guide chain struck the sea floor, and the Wadatsumi, halting its descent, pursued a course barely five feet from the bottom.
The water was clear at this depth. Once the flowing clouds of ooze had thinned, there was almost nothing to catch the light cast by the searchlight. The melancholy brown desert of the sea floor stretched all around them. The distant portion was grayish with a tinge of indigo. Beyond that was blackness.
“Well ...” said Onodera, breaking silence, his voice harsh, “this is the floor of the trench. The depth is 23,840 feet.”
As though jarred by Onodera’s voice, the two scientists began to exchange low, hurried whispers.
“Look there!” exclaimed Tadokoro, pointing his finger.
Yukinaga nodded. Running from west to east across the sea floor were any number of ripple marks.
“That over there,” said Tadokoro, “what’s that long thing like a rut?”
“I don’t know,” answered Yukinaga, shaking his head. He spoke to Onodera: “Could we turn in that direction?”
Onodera released a small amount of ballast. Once more a cloud of mud rose up outside the window. The Wadatsumi climbed a bit, and Onodera guided the nose of the submarine in the direction Yukinaga wanted by careful use of his jets rather than by the control stick, moving forward at extremely slow speed.
The long trench on the sea floor, some seven or eight feet wide, came into view through the cloud of muddy water. It looked as though some creature of fantastic size had dragged itself through the ooze.
“Over there, too,” Yukinaga whispered. “Why, there are all kinds of them.,,
“What do you think they are?” asked Tadokoro.
“I don’t know.” Onodera shook his head. “I’ve gone down into a trench two or three times now, but this is the first time I’ve ever seen anything like this.”
The sea floor was covered with these broad ruts. They ranged from fifteen feet in width to twenty or more. They extended east and west beyond the limits of the submarine’s field of vision. Something had caused the sea floor to shift. Some force of unimaginable power.
“Could it be that there was some extraordinary gravitational variation in this area?” Yukinaga asked.
“No idea,” answered Tadokoro. “Let’s follow along and have a look.”