They tasted the one bottle they've brought up so far before they even got back to shore.
Diving instructor Christian Ekstrom said the bottles are believed to be from the 1780s and likely were part of a cargo destined for Russia. The nationality of the sunken ship has not yet been determined.
"We brought up the bottle to be able to establish how old the wreck was," he said. "We didn't know it would be champagne. We thought it was wine or something."
Ekstrom said the divers were overjoyed when they popped the cork on their boat after hauling the bubbly from a depth of 60 metres.
"It tasted fantastic. It was a very sweet champagne, with a tobacco taste and oak," Ekstrom said.
The oldest known champagne currently on record is from 1825.
Link | Photo (unrelated) by Flickr user Waldo Jaquith used under Creative Commons license | Previously: World's Largest Champagne Flute