Da Dia Rapids is located in An Ninh Dong Commune, Tuy An District, Phu Yen Province. It is strangely structured rocks include large upright stones equally arranged in a star pattern.

Da Dia Rapids (or the Cliff of Stone Plates) is a baffling and beautiful riddle of Nature, and set in stone for all time. It's like a giant jigsaw, irritatingly made of the same shaped pieces, and forming a solidified structure that has proved more than just a curiosity for thousands. Looking down on it, visitors often liken it to a gigantic beehive, others as a pile of stone plates. For despite a lengthy series of historical, archeological and scientific probes of the cliff's square kilometer, its formation remains a mystery. Even counting the stone columns has failed to yield an exact figure as exhausted researchers usually call a halt at around 35,000.The stones are 60-80cm in visible height and 20-30cm across and cluster round a small fresh water pond that is fed by underground rivers and never dries up. Not surprisingly researchers find intriguing - and perhaps frustrating - comparison between.

The rapids have been listed as a National Heritage Site by the Ministry of Culture and Information.