Cat Ba National Park covers around 260 square kilometres of the eponymous island and includes one of the most biodiverse karst landscapes in southeast Asia. The forest grows on jagged limestone in patches of red soil and is home to macaques, civets, and the extremely rare Cat Ba langur — a golden-headed monkey found nowhere else on earth.
The park's main interest for visitors is hiking. A handful of marked trails leave from the park headquarters; the most popular is the four-hour walk to the summit of Ngu Lam peak, which offers a wide view over the karst interior. Hiring a guide is sensible — the trail markings are sparse and the limestone karst is genuinely confusing terrain to navigate. The dry winter months (November to March) are the easiest time to walk.