If someone or something that has been under water resurfaces, they come back to the surface of the water again. George struggled wildly, going under and resurfacing at regular intervals
If someone who has not been seen for a long time resurfaces, they suddenly appear again. It is likely that they would go into hiding for a few weeks, and resurface when the publicity has died down. = reappear
If something such as an idea or problem resurfaces, it becomes important or noticeable again. These ideas resurfaced again in the American civil rights movement