One of Halong Bay's most remarkable formations is Cat Ba Island, 420 square km (162 square miles) of wildly steep spines of mountains, narrow valleys and waterfalls, lush wetlands, golden beaches, and one of Vietnam's most beautiful national parks, which protects about two-thirds of the island. The sea life in much of the surrounding inshore waters is also protected. Included in these ecosystems are tropical evergreen forests, 15 kinds of mammals (including wild boars and hedgehogs), 200 species of fish, 21 species of birds, and 640 species of plants. Don't expect to see many wild mammals, however, such as the endangered langur monkeys that supposedly swing from the trees.
In 1938 a French archaeologist found traces of an ancient fishing culture on the island dating from the end of the Neolithic Era. Human bones alleged to be 6,000 years old were also found. More recently, during the Vietnam War, American bombers targeted the military and naval station here, causing numerous casualties and forcing hospitals to set up in nearby caves on the island to avoid the bombings. An ethnic Chinese community numbering about 10,000 settled on Cat Ba over the years, only to leave en masse in 1979 after Chinese troops invaded Vietnam in the brief but bloody border war of that year. The ethnic Chinese, or Hoa, sailed in dinghies to Hong Kong and other Asian ports, many dying along the way. Few ethnic Chinese have returned to Cat Ba.
Today the population of more than 20,000 continues to subsist on fishing and rice and fruit cultivation, but tourism is quickly becoming Cat Ba's primary cash crop. The beaches, particularly the lovely curved stretch of sand just over the hillside from the southeast corner of the wharf, are infinitely nicer than most of the others in Northern Vietnam. Walk off your seafood dinner by heading to the nearest beach, where you can sip iced coffee and watch the shooting stars. Splendid caves, just off the road to the national park, are great for exploring. Hiking through Cat Ba can be strenuous: the mountain ridges are steep, trails are poorly marked, and roads are narrow, making blind crests somewhat dangerous. Talk to your hotel manager or one of the many local tour operators about the best hiking trails for your level. A hike through the park—through the tropical forest to a rocky peak overlooking much of the island—is best undertaken with a guide. The park is also a favorite spot for Vietnamese tourists, many of whom seem to be able to scale the slippery rocks in stiletto heels.