Scenic falls in the city of Sioux Falls.
Falls Park in Sioux Falls is one of the most popular attractions in the area, and for good reason. It is a beautiful park in the heart of the city, spanning 123 acres and consisting of waterfalls, trails, a lookout, and a café.
Paved sidewalk trails run all around the falls and offer great lookout spots to sit by the falls or take some pictures. Be sure to visit in the winter when they're frozen over and, in December, they light up the falls and turn it into an amazing wonderland of nature and lights.
If you're in the Sioux Falls area, I'd definitely recommend checking the park out. It's free and can be a short trip or a day-long activity.