Rio de La Plata (River of Silver) is the last name of this Italian made vessel. Built in 1923 with the name "Principessa Maria", this 8,539 tons ship was sold on 1941 from its original manufacturer, Lloyd Sabaudo to Argentina, when it got its last name.
During summer of 1943, the Rio de la Plata (RdP, from now on) arrived to Acapulco bay, carrying mostly passengers but with a fully filled cargo bays. As soon as the ship entered Acapulco, the captain gave the order of disembark, to all passengers and the crew. The story tells that the captain took this decision because three American battleships where waiting for RdP to leave the bay. After calling with the ambassador of Argentina in Mexico City, the captain gave the order of disembark to the rest of the crew, and took the ship to the middle of the bay.
The next day, all the passengers and crew saw a big column of smoke going out the main deck of RdP, followed by a big fire. After noticing the fire, the port authority tried to move the vessel near the port so they could extinguish the fire. The RdP's captain, which intentions where to destroy the ship, decided to open the gates and sink the ship.
Lots of explanations have been given for the captain's acts and for the cargo that was inside the ship. Some people say that RdP had 13 tons of copper (which never was found). Other people say tha RdP was carrying mercury, a metal that was prohibited on those days. Documents that proved that Argentina was allied with Germany.
No one knows for sure what was the secret of El Rio de la Plata.