Cat Ba Island is the best stop if you want to do something else besides exploring the deep turquoise waters. The island has three beaches that perfect for swimming; Cat Ba National Park that covers one-third of the island; and a number of tourist attractions connected to the Vietnam War—more notably the Hospital
Cave, an underground, bomb-proof hospital and safe house.
Cat Ba is also the starting point for adventurers wishing to get up close and personal with Halong Bay. This is the best place to get a kayak, join a tour to explore the caves on the island, take off on a hike through the national park or do some rock climbing.
How to get there from Ha Long: high speed boat or Tuan Chau – Cat Ba ferry