The ship in question, the galleon Our Lady of Juncal, was part of a fleet hit by a powerful storm in 1631 in "one of the greatest tragedies that has ever occurred in Mexican waters," according to Mexico's National Institute of Anthropology and History.
The proposal by Odyssey Marine Exploration Inc. of Tampa, Florida, "is not intended to conduct research and does not have the approval of archaeologists or an academic institution of recognized prestige," the Institute said. It added that "treasure hunters have always had their eyes on" the wreck site.
Odyssey Marine chairman Greg Stemm said in a statement that "the proposal presented to Mexico for archaeological services is in compliance with the UNESCO Convention and would keep all cultural artifacts together in a collection."
The United Nations Educational, Scientific and Cultural Organization says on its Web site that the convention aims to "preserve in situ all remains of human existence submerged for at least one hundred years."