Da Dia Reef (Gành Đá Đĩa) is located in An Ninh Dong Commune, Tuy An District, Phu Yen Province, about 35–40 km north of Tuy Hoa City. It is one of the most prominent natural landscapes along the South Central Coast of Vietnam and has been recognized as a national scenic heritage site.

The distinctive feature of Da Dia Reef is its rare geometric basalt rock structure, formed by volcanic activity millions of years ago. The site is considered one of the few places in the world where this type of terrain can be found.

According to geological studies, Da Dia Reef was created when molten volcanic lava flowed into the sea. Upon contact with cold seawater, the lava cooled rapidly and contracted, forming natural cracks. This process caused the basalt mass to split into rock columns with hexagonal, pentagonal, and other polygonal cross-sections.

The columns stand tightly together in vertical formations. From a distance, they resemble stacks of plates layered on top of one another, which is why the site is called “Da Dia” (Stone Plates). This type of columnar basalt formation is rare and appears only in a few locations worldwide.

Key Features of Da Dia Reef

• Thousands of closely connected basalt columns forming a wide coastal surface
• Column shapes mainly hexagonal and pentagonal
• Natural layered formations resembling stacked stone slabs
• Located directly along the shoreline, with waves interacting with the rock surface
• This structure holds both geological scientific value and scenic landscape value.

Best Time to Visit

• Dry season (March – September): less rain and easier travel
• Morning: favorable lighting for observing the terrain
• Avoid days with strong waves or heavy rain

Visitor Notes

• Wear shoes with good grip as the rock surface can be slippery
• Avoid standing near the edge when waves are strong
• Do not climb unsafe areas
• Keep the environment clean and avoid damaging natural rock formations

Da Dia Reef is a representative geological attraction of Phu Yen Province, notable for its rare geometric basalt columns formed by ancient volcanic activity. Thanks to its convenient access and distinctive scenery, it is commonly included in travel itineraries along the Central Vietnam coastline.