Along the coast of Vietnam, there are many pebbles and gravel, but one of the most unique and interesting ones is Da Dia reef in An Ninh Dong commune, Tuy An district, Phu Yen province, about more than 40 km away from Tuy Hoa city, and about 11 km away from Chi Thanh town to the East.
Da Dia reef has the width of approximate 50 m and the length of more than 200 m which is a natural beauty spot which is hardly found. Stones here are placed in columns closely together with hexagonal shapes or round shapes as dishes placed together so it is called Da Dia reef.
According to the soil survey, stone in Da Dia reef is basalt stone formed from the activities of volcano of millions of years ago. Mineral from the volcano mouth was hardened when combining with sea water which also created forces to cause cracks for the whole mineral block along the vertical, horizontal, slanting joints to cut stone columns into many sections.
Next to Da Dia reef, there is Bai Bang with the length of approximate 3 km with fine white sand and clean and blue sea water which are favorable conditions for establishing a sea resort. This place still keeps the pristine beauty and pure environment. Ganh Da Dia shall surely leave unforgettable feelings in the mind of the visitors once they come to this place.
Da Dia reef is recognized by Ministry of Culture and Information as a national relic on 23/01/1997. In 2014, this place was ranked in Top 20 Most-wanted destination of Vietnam by Vietnam Records.