Located 25 km north-east of Quan Cave, next to the “stone park" in Ha Long is a cave with quite strange name of Thay Cave (Master Cave). the director of the Vietnam Conservation Centre of Heritage and Marine Entertainment Duong Nguyen explained that the name of the park is due to dozens of rocky islands here have different characteristics from those in Sung Sot Cave (Surprise Cave), and Thien Cung Cave. Meanwhile the structures of stones in Thien Cung cave and Sung Sot Cave have vertical direction; those in Thay Cave have horizontal direction. Each Stone Mountain contains hundreds of thousands stone blocks which were heaped up together look like stacks of giant books.

Thay Cave