In northern Minnesota, there are several wilderness areas to camp, especially on the northern border with Canada and the northwestern border with Wisconsin. Gooseberry Falls State Park is a beautiful park, full of wild berries and waterfalls. There are several hiking paths and several waterfalls in the area. There are the upper, middle, and lower falls, all offering spectacular views. At several areas of the falls, you are able to walk into the water flowing, and if it's nice and sunny outside, it's beautiful!
Camping in this area gets chilly as early as late August and doesn't really warm up until mid-June, so plan accordingly. I camped here once over Memorial Weekend, and it snowed! This is a great place to bring the family, though. They have several kid-oriented activities going on throughout the day, and there will not be a lack of friends for your youngsters to play with.