Opened in 2004, Supullo Unsimni is situated on the Namhangang Riverside. The site used to be a sandpit before it was turned into a wetland. Effluent from wastewater treatment plants, which in the past was released directly into the Hangang River, now passes through several ponds with various aquatic plants and a one kilometer-long waterway so that it can be naturally purified. This has contributed to an improvement in the water quality of the Hangang River. The center was built to restore the Namhangang Riverside area, which was destroyed due to sand extraction, and to restore its natural ecology of willow trees, reeds, and birds. The center organizes a number of ecological excursion programs for children.