Answer:
fortune hunters encounter many difficulties when exploring a shipreck.
The topic is "exploring a shipwreck" and the controlling idea is "many difficulties."
Step-by-step explanation:
Essentially, it conveys the main idea of a paragraph. When used throughout an essay, topic sentences make up its backbone, giving your arguments a clear support system. They help guide you as the writer, keeping your arguments on point, and they also help guide the reader.