Before most people had ever seen a coral reef in colour, Jacques Cousteau took television audiences beneath the waves with a red toque, a French accent, and the calm authority of a man who had personally negotiated with the ocean. "The Undersea World of Jacques Cousteau" made sharks, shipwrecks, and sea monsters feel less like dangers and more like neighbours - albeit neighbours with teeth. For decades it was appointment viewing - part science documentary, part adventure serial, and part reminder that the world below the surface was stranger, lovelier, and more fragile than anyone above it suspected.