Near the end of the Wuhu Town, near the ocean and over the Wuhu Island River.
The Red Iron Bridge (known as Harbor Bridge in its debut in Wii Fit) is a large cable-stayed bridge on Wuhu Island. The bridge is a iconic landmark, and is partly constructed out of iron, as the name suggests. The bridge goes over Wuhu Island River. The Island Loop Road has a section going over this bridge, as well. Some cycling races go past this bridge.
A common misconception is that the Red Iron Bridge is a suspension bridge. It is not; it is actually a cable-stayed bridge. Suspension bridges have cables coming down from each tower anchored to the ground, with other cables attached between these cables and the bridge. The bridge is suspended from these cables, hence, "suspension bridge." Cable-stayed bridges (like the Red Iron Bridge) have various cables attached directly between the tower and the bridge. The cables hold the bridge in place, hence, "cable stayed bridge."