At the heart of Cat Ba Island lies a visually stunning and ecologically diverse national park. In 1986, 9,800 [98 km²] hectares (approximately one third of the Island's total land mass) was annexed as Cat Ba National Park, the first decreed protected area in Vietnam to include a marine component (Dawkins 14). It had previously been the site of a timber company. In 2006, the boundaries of the national park were redefined, so the park contained 109 km² of land area and an additional 52 km² of inshore waters and mangrove covered tidal zones (langur website).
The domain of the endangered Cat Ba Langur, of which there are supposed to be only around 100 left. Things on offer include a walk to a peak viewing tower (1.5-2 hours round trip; slippery and muddy if it's rained recently), a frog pond (probably better in the off (wet) season), a short nature walk near the frog pond. The park is staffed by 92 people, including over 60 park rangers. In 2004, Cat Ba Archipelago was declared a UNESCO Man and Biosphere Reserve Area in order to protect the multiple terrestrial and aquatic ecosystems as well the diverse plant and animal life that is found on the Island.