The world he knew, the peaceful happy world of the surface, was like a pretty lake in which were reflected the dappled clouds and the willows that grew on its bank, where carefree boys paddled their canoes and the girls with them trailed their fingers in the soft water. It was terrifying to think that below, just below, dangerous weeds waved tentacles to ensnare you and all manner of strange, horrible things, poisonous snakes, fish with murderous jaws, waged an unceasing and hidden warfare.