“What should it have done?” asked Terry. “I’m not familiar with meteorites. Are they planning to dive for it?”
“Hardly!” Deirdre laughed. “It landed in the Luzon Deep.” She waved a hand in an inclusive gesture. “This island’s on the brink of it. A bathyscaphe might go down there—in fact, I think it’s scheduled; you know, the one I said was coming to Manila on the oceanographic ship? A bathyscaphe can go that deep, but it’s not likely to hunt for meteorites.”
“Ah,” said Terry judicially. “Then what difference does it make where it hit?”
“It didn’t fall the way it should have,” said Deirdre. “It was spotted by space radar away out, and they tried to compute its path, but they figured it wrong. Now they’re trying to make it come out right by allowing for the effect of the earth’s magnetic field on a metal meteorite. They’re arguing and waving equations at each other.”
“Let them,” said Terry. “I have trouble enough with fish. Do you think I could borrow a boat?”
“We’ve always been able to,” said Deirdre. Then she added, “I’ve kept your breakfast hot. While you eat it I’ll get a boat.”
She went below, and instants later was up again.
“I have a feeling,” she said, “that something interesting is going to happen. I’ll be back.”
She swung lightly to the wharf and headed for land. Terry went below, to find his breakfast laid out on the cabin table. He settled down to it, but first pulled a book from the shelves. It was a volume on oceanography, and its pages showed that it had often been referred to. He found the Luzon Deep described. Its area was relatively small, a mere ninety-mile-long chasm in the sea-bed. But it was second only to the Mindanao Deep in its soundings, and a close second at that. Its maximum depth was measured at twenty-seven thousand feet. Over five miles. There was a mention of Thrawn Island as being on the very edge of the Deep. According to the book, the island was the peak of one of the most precipitous and tallest submarine mountains in the world. Three miles from where Thrawn Island lay, there were soundings of twenty-eight thousand feet and upward. This depth extended as a trench. …
The staccato roaring of an outboard motor sounded some distance away. It bellowed toward the yacht, swung about, and cut off. Terry gulped down his coffee and went abovedecks, just as Deirdre was fastening the small craft alongside the yacht.
“Taxi?” she asked amiably. “I got the boat. Where to?”
Terry swung down and took the steering grip. He headed the boat away. There was a box for bait, a few fishing lines, and even two highly professional fish-spears on board. Fishing was not necessarily a sedentary pastime here.
“We try the lagoon entrance,” he said. “I’ve an idea. I noticed something last night, when we came in.”
“Do you want to brief me?”
“I’d rather not,” he admitted.
Deirdre shrugged without resentment. The little craft went sturdily toward the passageway to the open sea. She formed an arrowhead of waves as she moved. She neared the points of land at the ends of the coral formation enclosing the lagoon. Thrawn Island was not an atoll. But the beaches were made of snow-white coral sand. Outside there was clear water for a space and then a reef on which the seas broke.
Terry headed the boat toward the open sea. Almost immediately after, there was nothing but the reef and the sea between the boat and the horizon. He slowed the boat almost to a stop, well within the reefs tumult. She swayed and rolled on the surging water.
“Stay here,” he commanded. “I want to swim out and back.”
He pulled the sweat shirt over his head. He jumped overboard, leaving Deirdre in charge of the boat.
The world looked strange to him when waves rolled by higher than his head. A few times the sky narrowed to the space between wave-crests. Other times he was lifted upon a wave-peak, and the sky was illimitably high and large, and the breaking seas on the nearby reef merely roared and grumbled to themselves.
He swam out, away from the land. Suddenly his body began to tingle. He stopped and paddled, analyzing the sensation. One side of his body felt as if the most minute of electric currents entered his skin. It was not an unpleasant sensation. Deirdre, in the small boat, was fifty yards behind, watching him. As he swam on, the tingling grew stronger. He dived. The tingling did not vary with depth. He came up, and he was farther out than he’d realized.
He suddenly knew that he’d been incautious. There are currents which flow in and out of lagoons. A barrier of reef affects them, too. Terry found himself swimming in an outward-bound current, which pushed him out and away from the island.
Within seconds the sensation in his body changed from a mere tingling to torment. For a moment it was just very much stronger and slightly painful, but a moment later it felt as if he swam among flames. It was unbearable. His muscles were not contracted, as if by an electric shock, but he couldn’t control their reflexes. He found himself splashing crazily, trying to fight his way out of the anguish which engulfed him.
He went under. His body had taken complete control over his mind, and he found himself swimming frantically, underwater. He couldn’t reach the surface. His body tried to escape the intolerable agony in which it was immersed but couldn’t.
He heard a roaring sound, but it meant nothing. The roaring grew louder. Finally, he did break surface for a few seconds, and he gasped horribly, but then he went under. The roaring grew thunderous, and he broke surface again…
Something seized his flailing arm and pulled him up. The arm ceased to experience the horrible sensation of being in boiling oil. His hand recognized a gunwale. He swarmed up the solid object with hands helping him, and found himself in the boat, gasping and shivering, and cringing at the bare memory of the suffering he’d undergone.
Deirdre stared at him, frightened. She swung the boat’s bow shoreward. The outboard motor roared, and the boat raced past the gap in the reef and rushed toward the lagoon opening.
“Are you all right? What happened? You were swimming and suddenly…”
He swallowed. His hands quivered. He shook his head and then said unsteadily. “I meant to … check the reason those queer fish stay in the lagoon. I thought that if they belonged in the depths and were somehow carried out of them, they would try to get back. I found out!”
He felt an unreasonable relief when the lagoon entrance was behind the boat. The glassy water was reassuring. The Esperance looked like safety itself.
“I, think I know how they got here, now,” he added. We underestimated what we’re trying to understand. I’ll be all right in a minute.”
It was less than a minute before he shook himself and managed to grin wryly at Deirdre.
“Was there a hum in the water?” asked Deirdre, still staring at him. “I thought I heard it on the bottom of the boat. Was that the trouble?”
“Yes. I wouldn’t call it a hum,” Terry admitted. “Not any longer. Now I know what a slow fire feels like.”
“You frightened me,” said Deirdre, “the way you splashed…”
“Iheard the humming sound,” said Terry, “last night when the yacht came up to the island. We were perhaps a half-mile off-shore. It was very faint, but I had the amplifier turned down low. The hum was at its loudest just before we passed the reef, but nobody else noticed. When Dr. Morton said there were abyssal fish in the lagoon, I knew why they’d be there. I made a guess at what might drive them there. I went to find out if I was right. I found out!”
“The hum?” asked Deirdre again. When he nodded, she said: “What are you going to do now? What do you think makes the hum?”
“I’m trying hard not to guess what makes the hum,” Terry told her. “Insufficient data. I need more. I think I’ll ask what other odd phenomena have turned up in this neighborhood. Foam-patches on the sea? I can’t imagine a connection, but still …”