Uncover a piece of wartime history at Hospital Cave (Hang Quan Y), located within Cat Ba Island, often visited en route to the National Park. This large natural cave was ingeniously converted into a secret, bomb-proof hospital and safe house between 1963 and 1965, serving Viet Cong soldiers and leaders during the Vietnam War.

Visitors can explore the multi-level facility, which included operating rooms, wards, and even a cinema room and swimming pool built deep inside the mountain. Visiting Hospital Cave Cat Ba Island history site provides a fascinating look at Vietnamese resilience and ingenuity during a difficult period.