Phong Nha is a region defined by what lies beneath its surface. This project moves between two contrasting caves within the Phong Nha–Kẻ Bàng karst system: Paradise Cave, a vast dry cavern reached by a long staircase and explored along wooden boardwalks, where towering stalagmites and stalactites are shaped by hundreds of thousands of years of mineral deposit, and Hang Tiên, part of the Tú Làn cave system, accessible only through a jungle trek and defined by narrower passages, rougher textures, and a more raw, unlit relationship with the rock. The images follow this shift in scale and access: from the cathedral-like chambers of Paradise Cave, where artificial light reveals formations the size of buildings, to the darker, more physical experience of Hang Tiên, where daylight enters only through the cave mouth and human presence becomes a visible measure against the stone. Between these two sites, the surrounding landscape of misty limestone peaks and forested valleys frames the caves as part of a continuous geological system rather than isolated attractions. The work treats Phong Nha not as a single monument, but as a layered environment where infrastructure and wilderness meet underground.