Vanhankaupunginkoski

This guide to Vanhankaupunginkoski in Helsinki follows a 2020 study that tagged sea trout, salmon and whitefish with radio trackers to see whether they could get past these urban rapids at all. It traces the dam back to 1874, and further still to King Gustav I's trading town founded here in 1550, through the watermills and floods that eventually pushed the city south. You'll hear how two attempts to build a fish ladder, in 1986 and again years later, changed what the tagged fish actually did at the base of the old dam. Look for the red brick mill buildings still standing along the bank.