Duluth, Minnesota four Catholic schools with coverage up to grades 6 or 8, two Protestant schools, two Montessori schools, and six other charter and private schools. Due to its proximity to the Great Lakes, Duluth is the location for the Large Lakes Observatory. The Large Lakes Observatory operates the largest university-owned research vessel in the Great Lakes, the R/V Blue Heron. Built in 1985 for fishing on the Grand Banks, the Blue Heron was purchased by the University of Minnesota in 1997, sailed from Portland, Maine, up the St. Lawrence Seaway to Duluth, and converted into a limnological research vessel during the
Minnesota Seaway east to the Atlantic Ocean, or the Hudson Bay watershed to the Arctic Ocean. The state's nickname, "Land of 10,000 Lakes", is apt, as there are 11,842 Minnesota lakes over in size. Minnesota's portion of Lake Superior is the largest at and deepest (at ) body of water in the state. Minnesota has 6,564 natural rivers and streams that cumulatively flow for . The Mississippi River begins its journey from its headwaters at Lake Itasca and crosses the Iowa border downstream. It is joined by the Minnesota River at Fort Snelling, by the St. Croix River near Hastings, by