Bothnian Sea National Park is a national park in Finland. It was established in early 2011. Around 98% of the surface of the National Park consists of water.
Wikipedia https://en.wikipedia.org/wiki/Bothnian_Sea_National_Park
More information on outdoors.fi http://www.outdoors.fi/destinations/nationalparks/bothniansea/Pages/Default.aspx
Coordinates 62°17'54.892" N 20°25'24.902" E
