Cat Ba's beautiful national park is home to 32 species of mammal, including most of the world's 65 remaining golden-headed langurs, the world's most endangered primate. There are some good hiking trails here, including a two-hour return trip to Ngu Lam peak and a day-long hike to Viet Hai village. To reach the roadside park headquarters at Trung Trang, hop on the Song Tung bus from Cat Ba Town, or hire a xe om (around 80,000d one way) or a car (US$30 return).
A guide is not mandatory but is definitely recommended. Many visitors opt to visit the park on an organised tour from Cat Ba Town, but you can also arrange guides at the park headquarters.
The short but strenuous hike to the top of Ngu Lam peak (park guide 200,000d) brings views over the surrounding jungle. The challenging 9km hiking trail through the park (starting just north of the park entrance) to the village of Viet Hai is best done with a guide (500,000d to 700,000d). Lunch and homestays are available in Viet Hai. From here you can walk, rent a bicycle (75,000d) or take an electric vehicle for 5km to the pier, where taxi boats shuttle back to Ben Beo Pier (300,000d to 500,000d per boat) near Cat Ba Town until 4pm. An elusive shared public ferry (50,000d per person, one hour) should depart from Ben Beo at 11am and 4pm, and from Viet Hai at 7am and 1pm but check these times.
Take proper hiking shoes, a raincoat and a generous supply of water for the Viet Hai hike. This is not an easy walk, and best avoided during the wet season or after rain.
Of the mammals present in the park, the more commonly seen include macaques, deer, civets and several species of squirrel, including the giant black squirrel. Seventy bird species have been spotted here, including hawks, hornbills and cuckoos.