Final answer:
The people of Amity Harbor are likely frightened about maritime dangers, which include the potential for shipwrecks or being lost at sea.
Step-by-step explanation:
The people of Amity Harbor are frightened about the possibility of danger at sea, such as shipwrecks or getting lost. The passages provided expound on various states of fear and contemplation that come with maritime voyages and the sight of ships.
Sailors might fear shoal waters, while onlookers may feel a blend of awe and dread at the majesty and perils of the ocean. The imaginative potential for disaster can be as harrowing as tangible threats for those like the characters in LibreTexts™ who experience the ocean's vastness and the risks involved with navigating it.