Dolphin Island by Arthur C. Clarke

seen since the glare and smoke of cities spread across the
     world and dimmed the splendor of the skies. It was the Zodiacal Light, which astronomers
     puzzled over for ages until they discovered that it was a vast halo of dust around
     the Sun.
    Soon afterward, Mick caught his first crayfish. It was crawling across the bottom
     of a shallow pool, and the poor creature was so confused by the electric glare that
     it could do nothing to escape. Into Mick’s sack it went; and soon it had company.
     Johnny decided that this was not a very sporting way to catch crays, but he would
     not let that spoil his enjoyment when he ate them later.
    There were many other hunters foraging over the reef, for the beams of the flashlights
     revealed thousands of small crabs. Usually they would scuttle away as Johnny and Mick
     approached, but sometimes they would stand their ground and wave threatening claws
     at the two approaching monsters. Johnny wondered if they were brave or merely stupid.
    Beautifully marked cowries and cone shells were also prowling over the coral; it was
     hard to realize that to the yet smaller creatures of the reef, even these slow-moving
     mollusks were deadly beasts of prey. All the wonderful and lovely world beneath Johnny’s
     feet was a battlefield; every instant, countless murders and ambushes and assassinations
     were taking place in the silence around him.
    They were now nearing the edge of the reef and were splashing through water a few
     inches deep. It was full of phosphorescence, so that with every step, stars burst
     out beneath their feet. Even when they stood still, the slightest movement sent sparkles
     of light rippling across the surface. Yet when they examined the water with the beams
     of their flashlights, it appeared to be completely empty. The creatures producing
     this display of luminescence were too tiny, or too transparent, to be seen.
    Now the water was deepening, and in the darkness ahead of him, Johnny could hear the
     roar and thunder of waves beating against the edge of the reef. He moved slowly and
     cautiously, for though he must have been over this ground a dozen times by day, it
     seemed completely strange and unfamiliar in the narrow beams of the flashlights. He
     knew, however, that at any moment he might stumble into some deep pool or flooded
     valley.
    Even so, he was taken by surprise when the coral suddenly fell away beneath his feet
     and he found himself standing at the very brink of a dark, mysterious pool. The beam
     of the flashlight seemed to penetrate only a few inches; though the water was crystal
     clear, the light was quickly lost in its depths.
    “Sure to find some crays here,” said Mick. He lowered himself into the pool with scarcely
     a splash, leaving Johnny standing above, half a mile from land, in the booming darkness
     of the reef.
    There was no need for him to follow; if he wished, he could remain here until Mick
     had finished. The pool looked very sinister and uninviting, and it was easy to imagine
     all sorts of monsters lurking in its depths.
    But this was ridiculous, Johnny told himself. He had probably dived in this very pool
     and had already met all its inhabitants. They would be much more scared of him than
     he would be of them.
    He inspected his flashlight carefully and lowered it into the water to check that
     it continued shining when submerged. Then he adjusted his face mask, took half a dozen
     fast, deep breaths, and followed Mick.
    The light from the flashlight was surprisingly powerful, now that both he and it were
     on the same side of the water barrier. But it revealed only the small patch of coral
     or sand upon which it fell; outside its narrow cone, everything was blackness—mystery—menace.
     In these initial seconds of Johnny’s first night dive, panic was not far away. He
     had an almost irresistible impulse to look over his shoulder to see if anything was
     following him….
    After a few minutes, however, he got control of