In Taiwan, humpback dolphins (Sousa chinensis) have only been sighted in the shallow, turbid western coastal waters. However, a single humpback dolphin was first sighted near the mouth of Fugang harbor in the southeastern coast of Taiwan on 15 July 2005. Until this event, there had not been any recorded sighting of humpback dolphins in this region of Taiwan. Both water depth and bottom gradient in eastern waters of Taiwan are much deeper and steeper, respectively, than those in western coastal waters. There is no information on why the humpback dolphin was in this unusual habitat.