20,000 Leagues Under the Sea, by Jules Verne
Underwater Trip Around the World (Part I)
A Shifting Reef

The year 1866 was marked by a bizarre event, an unexplained and inexplicable phenomenon that surely no one has forgetten. Leaving aside the rumors that troubled the people living in the ports and got the public living inland worked up, seafarers were particularly disturbed. Merchants, shipowners, captains, skippers, and master mariners from Europe and America, navy officers from every country, and, after them, governments from various nations on the two continents, all were extremely worried about this event.