The main tourist attraction is the 7 km long and 4.2 km longest navigable underground river in the world,[2] which flows under the massif of the Karst Mountains (a limestone interspersed with fissures and cavities) with the 1027 m high Mt. St. Paul and then into the South China Sea. Only the first 1.2 km of the system are open to tourists, beyond that a special permit is required. Geologists estimate the age at 23 million years.

An up to 45 m high dome[3] was created by the collapsed overburden. The river is partly over 8 m deep, in many places stalagmites and stalactites, organ pipes, curtains and domes have formed.

The main tourist attraction is the 7 km long and 4.2 km longest navigable underground river in the world,[2] which flows under the massif of the Karst Mountains (a limestone interspersed with fissures and cavities) with the 1027 m high Mt. St. Paul and then into the South China Sea. Only the first 1.2 km of the system are open to tourists, beyond that a special permit is required. Geologists estimate the age at 23 million years.

An up to 45 m high dome[3] was created by the collapsed overburden. The river is partly over 8 m deep, in many places stalagmites and stalactites, organ pipes, curtains and domes have formed.

The main tourist attraction is the 7 km long and 4.2 km longest navigable underground river in the world,[2] which flows under the massif of the Karst Mountains (a limestone interspersed with fissures and cavities) with the 1027 m high Mt. St. Paul and then into the South China Sea. Only the first 1.2 km of the system are open to tourists, beyond that a special permit is required. Geologists estimate the age at 23 million years.

An up to 45 m high dome[3] was created by the collapsed overburden. The river is partly over 8 m deep, in many places stalagmites and stalactites, organ pipes, curtains and domes have formed.

The main tourist attraction is the 7 km long and 4.2 km longest navigable underground river in the world,[2] which flows under the massif of the Karst Mountains (a limestone interspersed with fissures and cavities) with the 1027 m high Mt. St. Paul and then into the South China Sea. Only the first 1.2 km of the system are open to tourists, beyond that a special permit is required. Geologists estimate the age at 23 million years.

An up to 45 m high dome[3] was created by the collapsed overburden. The river is partly over 8 m deep, in many places stalagmites and stalactites, organ pipes, curtains and domes have formed.