The Mysterious Disappearance of kaiko.
For eight years, a tough little submarine worked in the deepest, darkest place on Earth. It explored the ocean floor in terrible condition. The pressure there is about 1000 time greater than at the ocean's surface. No light from the sun ever reaches so deep. Then the submarine, Kaiko, suddenly disappeared. What happened? Did the extreme conditions kill Kaiko? Where did Kaiko go?