In those days, the wrecks were easy to find in the relatively shallow waters of the Keys — since they had not yet been covered by ocean subsidence or algae, nor had their hulls decomposed — but the Spaniards were unable to retrieve any of the treasure, for lack of diving equipment.
While scouting the sea bottom, Donald, Huey, Dewey, and Louie are menaced by sharks attracted by meat chunks dropped by the pirates, and duck under a shelf of rock that turns out to be the lip of an Imperial-era diving bell.
When they bring the bell up, Scrooge recognizes the name engraved on the side: Candelaria, the flagship of Francisco Núñez Melián's salvage fleet.
However, the two pirates return and board the schooner, tie up Scrooge, lower themselves to the wreck in the diving bell, and relieve the ducks of the camera at gunpoint.
The rush of water into the vented dome destroys the Candelaria, and forces Donald and his nephews to swim to the surface without their diving gear.