The Spanish 1715-Fleet disaster was probably the greatest to befall any of the Spanish treasure fleets in terms of casualties and money, with reports of a loss of 14 million pesos (plus an equal or greater amount in contraband) and as many as 1,000 or more lives. In typical fashion, the 1715 Fleet was a case of overloaded Spanish galleons foundering in a hurricane after delayed departure, but on a larger scale than anything before. 
The principal elements of the fleet, known as the Nueva España (New Spain, i.e., Mexico) Fleet, had gone to Veracruz in Mexico to deliver mercury (an essential substance in the refining of silver cobs), sell merchandise, and pick up quantities of Mexican-minted bars and cobs. An unfortunate series of complications kept the fleet in Veracruz for two whole years before it could rendezvous in Havana with the vessels of the Tierra Firme (Mainland) Fleet, bearing the Peruvian and Colombian treasure brought from Panama and Cartagena. After still more delays in Havana, what was ultimately a twelve ship convoy did not manage to depart for Spain until July 24, 1715, well into hurricane season.
The trip back to Spain was to be the routine one: up the coast of Florida on the Gulf Stream, which gradually turns outward into and across the Atlantic at about the location where the fleet was lost. On the 30th of July, the fleet encountered a hurricane, driving the ships shoreward. Some of the ships sank in deep water, some broke up in shallower water, and others ran aground close to the beach, Hundreds of the crews and passengers lost their lives while other hundreds of survivors improvised a camp on shore to await aid from the Spanish fort at St. Augustine, to which a party was sent. Ultimately, news of the disaster reached Havana, whence salvage ships were dispatched to the wreck.