Lämsänjärvi
Lämsänjärvi is a small lake located in the district of Oulunsuu in Oulu, Finland. There is a public beach on the northeast side of the lake which is maintained by the city and a church operated camp building on the west side which was built in 1936. The lake used to be very shallow overgrown swamp water but it was dredged in the early 1980s and converted in to its current form. Pedestrian and bicycle paths go around the lake as well as skiing and snowmobile trails in the winter. In 2014 the beach was closed after an outbreak  of diarrhea and vomiting amongst the swimmers and samples of the water were confirmed to have contained norovirus and adenoviridae which tend to spread easily in smaller bodies of water. The water quality is monitored closely and tested every year before the swimming season begins.