The tunnel, running between the Santalahti and Naistenlahti districts of Tampere is expected to be used by up to 45,000 vehicles a day, making it the most heavily-trafficked stretch of road in the country outside the capital.
Around 650 000 cubic metres of earth and stone were excavated during the construction project that began in 2013 and was completed six months ahead of schedule.
Tampere's Rantaväylä tunnel is 100 metres longer than the Karnainen road tunnel in Lohja which previous held the title as the country's longest.
