Cat Oan - Hon Xep is considered an open-air geological museum in the midst of Ha Long Bay.

Located in the World Natural Heritage site of Ha Long Bay, about 30km southeast of Tuan Chau International Port, Cat Oan - Hon Xep is regarded as an open-air geological museum in the middle of Ha Long Bay with wild and magnificent landscapes. The area contains rocky islands made of beautiful horizontal rock layers, and natural white sand beaches at the foot of the island.

This place looks like an overall architecture block consisting of many large and square stone blocks. The blocks are “stacked” on top of each other in rows, forming separated layers like an Egyptian pyramid in the middle of a quiet space. The architecture represents unique characteristics of the geological - geomorphological value of Ha Long Bay World Natural Wonders - Heritage Area.

Xep Islet

Here amidst the spacious and quiet space, the rocky islands with folded geological structures stack on top of each other to form a unified block. Clever and skillful arrangements by mother nature make visitors get lost in a huge geological museum on the surface of Ha Long Bay. With the nature of sedimentary rocks, the limestone islands in this area are originally horizontal, then experienced a long history of geological development with many periods of strong tectonic movement, creating complex fractures and folds. This natural architecture is living proof for the formation and development of Ha Long Bay.

The system of limestone islands, beautiful natural landscapes, and fine white sands formed from coral debris and mollusk shells are the elements that make up the value of this heritage.

Cat Oan beach

The Tung Ang ecosystem in this area is formed from sinkholes, Karst funnels, and closed valleys, surrounded by limestone islands and high mountains forming closed ravines. Therefore, the composition of flora and fauna in this area is rich and has unique characteristics, creating a beautiful and attractive habitat.

Thung grotto

Located in the southeast of Van Gio Island, Duc Tien Cave is a historical site on Ha Long Bay. It is a workshop where gun foundries and mints were set up to prepare for the resistance war against the French. In the cave, the stalactite system is still being formed, covered with sparkling calcite crystals with many unique shapes.

Tourists go kayaking in this area.

This is an outstanding cave attraction for visitors who are passionate about exploring and researching the geology, culture, and history of Ha Long Bay. In particular, tourists can choose to visit Dung Cave - an archaeological site belonging to the Soi Nhu culture, with its own unique features.