Gradually, word got out to the Champagne world, and this November experts from abroad, including from Jacquesson and Veuve Clicquot, were invited to Aland (pronounced AH-lahnd) to replace the crumbling corks in 10 bottles and for a tasting. In the meantime, the Champagne had become the property of the local government, which lays legal claim to anything found in undersea wrecks that is more than 100 years old.

The first three bottles recorked were Juglar, but on the bottom of the fourth cork were the star and anchor of Veuve Clicquot. The star represents a comet that crossed the skies of Champagne in 1811 and supposedly caused fabulous vintages. “I thought, ‘Madame Clicquot is watching us,’ ” Mr. Ekstrom said.

At another recorking, further bottles of Veuve Clicquot appeared. François Hautekeur, a Veuve Clicquot winemaker who attended, pointed to the name Werle branded into the bottom of the cork, referring to Édouard Werle, the man who in 1830 assumed much of the business from the Widow Clicquot, actually Barbe Nicole Clicquot, née Ponsardin, who inherited the company from her husband in 1805 and ran it until her death. “So it is later than 1831,” Mr. Hautekeur said.

Jean-Hervé Chiquet, whose family now owns and operates Jacquesson, the winery that absorbed Juglar, said that the shape of the bottles and the use of the name Juglar indicated the Champagne was from the late 1820s, and may have been stored for some time before it was shipped.

He was “overcome with emotion,” he said, when he first tasted the Champagne at the recorking in November.

“There was a powerful but agreeable aroma, notes of dried fruit and tobacco, and a striking acidity,” Mr. Chiquet said by telephone. The oldest Champagne in Jacquesson’s inventory is from 1915, he said.