The Ounasjoki river runs through the centre of Rovaniemi and defines the character of the city more than any single building. In summer, the river banks are walkable and cyclable, with the Arktikum museum sitting directly on the north bank and parkland along both shores. Canoe and kayak rentals are available, and the stretch of river through the city is calm enough for beginners. In July, the midnight sun turns the water gold at 11pm and stays gold until after midnight.
In winter the river freezes solid and becomes a winter highway — locals walk and ski across it, and some years snowmobiles use it as a shortcut between the city and the forests to the north. The ice fishing is excellent in late winter, with perch and pike being the main catches through holes cut in the ice. The spring breakup of the river ice is one of the most dramatic seasonal events in Finnish Lapland — great slabs of ice shift and crack over several days, and the river rises metres above its normal level as the Lapland snowpack melts.