The Blue World

This is classic a carefully thought-out world, a stratified society, and a man in conflict with its rules. During the space of twelve generations, the descendents of a crash on a water-covered planet have managed to adapt to the marine culture. But they are always at the mercy of the kragen, giant, squidlike monsters. The colonists can communicate with the biggest of these, King Kragen, and must appease him. But finally, one man has had enough of this life of slavery and sacrifice. Can he convince his fellow citizens that they must kill King Kragen? But...how can they do it in a world without weapons?