There was a news story some years ago about Greek amphorae (jugs) and coins found by scuba divers in a bay off the coast of Brazil or some other South American country. So either ancient Greek sailors made it to the New World, or someone transporting ancient Greek artifacts much more recently lost their cargo overboard.
The wreck is in the Bay of Jars, Rio de Janiero, was explored by Robert Marx in the 1960s, but the Brazilian gubmint kicked him out and forbade future study of the site.
Smugglers with contraband historical artifacts just throwing it overboard when about to be caught?