"Mary, you really are a great person. I hope we can keep in correspondence. I said I would write," the short message reads. "Your friend always. Jonathon. Nova Scotia 1985."
Kite surfer Matea Rezik discovered the note after it washed up in a bottle on the banks of the Neretva river.
Rezik told Croatian newspaper Dubrovacki Vjesnik she was helping clear a beach of debris when she spotted the plastic-coated note shoved into a bottle.
Rezik has since posted a photograph of the note on Facebook and said she'd love to get in touch with either Jonathon or Mary.
"Message in a Bottle! From Canada to the Neretva River estuary for 28 years!!" she wrote alongside the photo of the message.
The discovery is sparking much speculation about the relationship between the man and the woman and what might have become of them.
"Jonathan from NS, your message in a bottle landed in Croatia, 28 years after you sent it!" said one person on Twitter.
"I hope Mary knew Jonathon thought she was so swell!" tweeted another.
Some wondered how the Nova Scotian could have hoped to get his letter to Mary by surrendering it to the sea.
"And how did Jonathan think Mary would get his message?" mused one person on Twitter.
If the message in a bottle had been launched from Nova Scotia nearly three decades ago, it could have bobbed across the Atlantic, made its way into the Mediterranean Sea, possibly through the Strait of Gibraltar between Spain and Morocco, before floating up the Adriatic Sea to get to the river which brought it to the beach where it was found.
While some have marvelled at the length of the bottle's time at sea, the note from Nova Scotia was discovered sooner than other messages in a bottle.
Last April, a fisherman sailing off the northern coast of Scotland scooped up a bottle which had been at sea for 98 years.
Guinness World Records later confirmed that the find was the oldest message in a bottle ever recovered.
That bottle, which had been released in 1914, was set afloat in a batch of 1,890 others in a government experiment to map the undercurrents of the seas around Scotland. Inside each bottle, a postcard asked the finder to record details of the discovery.
_ By Diana Mehta in Toronto.Suggest a correction