This unique park makes for a fun day trip that is only about one hour from the twin cities. Go for a hike while enjoying the scenic prairies, forested hills, wetlands, and floodplains of the St. Croix River. William O'Brien State Park is 2,200 acres and full of wildlife. As you walk through the restored oak savanna, you will see many birds, butterflies, as well as dragonflies. You will also see beaver dams and diverse vegetation including an abundance of wildflowers in the spring and summer.