Imatrankoski Rapids are the reason Imatra exists on old travel maps. Catherine the Great visited in 1772, and later Russian and Finnish visitors treated the roaring Vuoksi as a natural spectacle worth crossing the country to see.
The river was dammed for power in 1929, so the rapids now run freely only during scheduled releases and special events. Even so, the gorge, bridges, and surrounding park keep their force; time your visit for a water release if you can.