Without waves and ripples, lakes, seas and oceans would scarcely be more attractive than simple swimming pools. Sometimes their swells become monstrous, ferocious, killer: freakish. How are these ogres of freak waves born, how do they live and die? Do they come out of nowhere? Can ships confront them? Here are a few thoughts on rare events, anecdotes and scientific explanations within everyone's reach, livened up with photos and watercolours.