Vietnam is bestowed with many captivating natural wonders that really rare places in the world do. About 40 km north of Tuy Hoa city, Phu Yen province, Da Dia Reef (Ganh Da Dia or Ghenh Da Dia in Vietnamese) is a seashore area of uniformly interlocking basalt rock columns located along the coast in An Ninh Dong Commune, Tuy An District, Phu Yen Province, Vietnam.
Da Dia Reef is structured with a surprising geology, including bountiful rocks in disparate shapes: circular, pentagonal, hexagonal or other polygonal looks. They are stacked together in a heap or fixed in pillars like plates overlapped each other. After surveying and testing sample, the geologists said that these are black and yellow basalt rocks. From a far corner, the whole area looks like a giant beehive.
According to scientific explanations, the shape of Ganh Da Dia was formed by the activity of volcanic eruptions millions of years ago. The molten lava fluid met the cold ocean. As the lava cooled, contraction and fracturing occurred and starting in a blocky tetragonal pattern and transitioning to multidimensional polygonal rocks today. In all over the world, besides Phu Yen, there are only other 3 places that have this magnificent phenomenon such as Giant’s Causeway in Ireland, Los Órganos in Spain and Fingal’s sea cave in Fingal, Scotland.
With more than 50 m wide and 200 m long, Da Dia reef is c onsidered a unique area in Vietnam and was recognized as a national heritage site in 1998. It becomes a must-see destination in Phu Yen province.