The majority smaller islets and karsts are capped with a low shrubby ’crown’ The larger islands are home to dense tropical forests featuring abundant bird life. The island of Cat Ba on the Southern flank of Halong Bay is a rich treasure trove for nature lovers. The National Park which occupies much of the island, and some of the surrounding waters, ranges in diversity from double-tiered primeval tropical rainforest on the slopes of the hills, down to tidal mangrove forests and inshore coral reefs. The island is home to several plant and tree species highly prized for their medicinal properties, and one of the rarest primate species on earth, the Cat Ba (Golden-headed) Langur. There may be as few as 50 of these animals between here and extinction.