With numerous hexagonal basalt columns formed inside a lava flow which cooled slowly and crystallized, Ghenh Da Dia (Cliffs of Rock Plates) is considered a masterpiece of rocks gifted by nature.
Located in An Ninh Dong commune, Tuy An district, Phu Yen province, Ghenh Da Dia is a natural columnar forming a very rare type of rocks. The cliffs are dark lava hexagonal columns with flat surfaces, resembling dinner plates. That gives rise to its name - Ghenh Da Dia.
The basalt cliffs at Ghenh Da Dia were said to be formed during a volcanic eruption in Van Hoa Plateau (Son Hoa district), about 30km from the recent site of Ghenh Da Dia. The eruption dated about 200 million years ago when lava flowed to the edge of the sea, suddenly hardened when meeting cool sea water. The huge solid block of basalt then cracked into vertical or oblique columns, and also horizontal cracks segmented each column into different pieces.
Ghenh Da Dia is about 50m wide and stretches over 2,000m long. Each column has an average visible height of 60-80cm, cross-section of 20-30cm. It is estimated that there are around 35,000 rock columns standing in close position as if they were closely put together by a supernatural hand. Looking from a distance, visitors may even liken Ghenh Da Dia to a huge beehive.
Ghenh Da Dia, half submerged below the surface of the sea, eroded by the ocean waves over the years, become extremely black and had pock-marked imprints of time.
It is worth noting that Ghenh Da Dia is a fresh water pond surrounded by rock columns. The pond is said to be fed by underground rivers and never dries up. It is really fantastic to sit on rock columns there to feel and see the high sky and the immense sea, breathe cool, and fresh air from the sea.