As convinced as many family members are that lifting the submarine and bringing it to shore is possible, experts are much less certain.

“There aren’t many precedents in the world of carrying out a feat of this magnitude,” said Fernando Morales, a navy expert and vice president of the Argentine Navy League. “It presupposes a feat of engineering that, even if possible, could demand one to two years of preparation, and even then may prove to be prohibitively expensive.”

Although some cited the example of a sunken Russian submarine, the Kursk, which was successfully raised from the seabed in 2001, that vessel was only 380 feet deep. The San Juan is almost 3,000 feet deep.

For Oliver Plunkett, chief executive of Ocean Infinity, there are other issues. Even if the submarine can be brought to shore, he said, when it got there, the vessel might not be in the condition that family members imagine. And it might not offer information helpful to the investigation.

“It may be technically impossible to lift it so that it comes on land looking exactly the same as it does on the seabed,” Mr. Plunkett said, emphasizing that it was still “far too early” to have a definitive answer.

Capt. Richard Bryant, a retired American Navy submarine commander, said recovery efforts at such depths are complex and rely mainly on vehicles operated remotely. Because of the age and condition of much of Argentina’s Navy fleet, its government is likely to seek international help.