American Astronauts, who had landed on the moon, reported after their return that the only living structure on Earth visible from the moon is the Great Barrier Reef. Ben Cropp and his wife Lynn spent 24 hours on this reef, watching the manifold life of this world beneath the sea, which is ruled by high and low tide. Just before sunrise, when the water is at it's lowest, schools of brightly coloured coral fish go out in the search for food. They are only safe from sharks when the water is shallow. Many animals have developed admirable techniques for the difficult struggle to survive. The squid for example, is a true artist, being able to change it's colour like a chameleon. There seems to be no life left on the reef after dark. The nocturnal animals only become visible by means of Ben's spotlights. Sea snakes, sharks and green sea turtles, the females of which lay dozens of eggs on the beach. At dawn they disappear again before the other animals wake.