The adventurous Swede set off on the 100 kilometre journey at midnight on Tuesday. But after just ten kilometres the vehicle sputtered to a stop and made its own way to the bottom of the Baltic.
Rehnberg was picked up by a support boat and returned to dry land, Västerbottens-Kuriren (VK) reports.
It was water from above rather than below that put paid to his travel plans, he explained, with rain seeping into the machine and killing the engine.
“Embarrassing,” he told VK, although he confessed he was relieved the engine hadn’t failed further out to sea.
Undeterred by the minor fiasco, Rehnberg said he would make another attempt to drive to Finland just as soon as he managed to dredge his snowmobile up from the bottom of the sea.