Earnest Rookey, of Jackson, and Carl Bayer, of Hillsborough were part of an expedition dive team, filling in for other crewmen who had dropped out, when they made the find 240 feet below the ocean surface, the Newark (N.J.) Star-Ledger reported Monday.
"This is an incredibly significant find," expedition group leader Joel Silverstein said. "Think of it like finding a needle in a haystack."
The 75-pound bell is 2 feet tall and bears the name of the ship.
Silverstein said the wreck site of the Andrea Doria, once considered Italy's flagship, has drawn thousands of divers who consider it the Mount Everest of SCUBA diving because of its remote location and challenging conditions, the newspaper said.
"Whenever you're that far out in the ocean, you're facing a lot of unknowns," Silverstein said, citing the unpredictable weather and fierce currents making for a tough dive.
Rookey and Bayer found the bell when they spotted a portion of it sticking out of the sand, the Star-Ledger said.
"This is an important find for the whole team," said Silverstein, "It wouldn't have been possible if we were not all in it together in the right place at the right time."
The Andrea Doria sank July 25, 1956, after colliding with the Stockholm. Forty-six people lost their lives but about 1,660 were saved.