Lock of the Emerald Sea

On a planet where oceans are filled not with water but with extremely dangerous organisms, on an island in the middle of the Emerald Sea lives a young man who is not at all pleased with his fate — the... fate of the only son of a duke, the future heir to the throne. One day, Charlie has to leave the island: his father takes him in search of a noble bride to arrange a profitable dynastic marriage. Farewell, Charlie promises the young commoner he loves that he will return and marry her. He promises — and does not return. Instead, the duke brings back a completely different young man, a distant relative, whom he declares his adopted son and heir. However, the girl manages to find out that Charlie was cast into the Midnight Sea, the most dangerous of the twelve seas of the planet. And now, to set off to rescue him, it is not enough to break the duke’s strict prohibition against leaving the island — one must invent a way to break it...
With colorful illustrations by the famous fantasy artist Howard Lyon!