The facts
| Figure | |
|---|---|
| Area | 262.41 km² |
| Population | 18,934 in 2021 |
| Archipelago | 367 islands, southeastern edge of Lan Ha Bay |
| National park | Established 1986, 9,800 ha, redrawn 2006 to 109 km² land and 52 km² water |
| Biosphere Reserve | UNESCO, since 2004 |
| World Heritage | Part of Ha Long Bay and Cat Ba Archipelago since 2023 |
| Cat Ba langur | About 68 in the wild, down from 2,400 to 2,700 historically |
| Distance | 50 km from Haiphong, 150 km from Hanoi |
Disclosure: VietSIM sells prepaid eSIMs for Vietnam. We sell no tours, book no boats and have no relationship with any operator on the island.
What it is next to
Cat Ba sits at the southeastern edge of Lan Ha Bay, at the head of an archipelago of 367 islands, adjoining the karst seascape that made the region famous. Since 2023 the World Heritage site has covered both, as Ha Long Bay and Cat Ba Archipelago.
That extension is recent enough to matter when you plan. A great deal of published material still treats Cat Ba as the cheaper alternative next door rather than as part of the same inscribed landscape, and prices and crowds have not finished adjusting to the change.
The practical difference is what you sleep on. Ha Long is largely experienced from a boat. Cat Ba is an island with a town, 18,934 residents as of 2021 and 262.41 square kilometres of land, so you can base yourself there and go out into the bay rather than living on the water.
The park, and the reason for its rules
Cat Ba National Park was established in 1986 covering 9,800 hectares, about a third of the island, and redrawn in 2006 to 109 square kilometres of land with a further 52 square kilometres of inshore water. The archipelago has been a UNESCO Biosphere Reserve since 2004.
The reason for the strictness has a number attached. The Cat Ba langur lives nowhere else. Its population had been somewhere between 2,400 and 2,700, collapsed to as few as 53 in 2000, and now stands at roughly 68 in the wild.
Cat Ba langurs, a primate found nowhere else
Sixty-eight animals is not a conservation statistic you can be casual about. Stay on the marked routes, do not go looking for them, and treat the guide’s instructions as the point of having a guide.
Getting there
The island is 50 kilometres from Haiphong and 150 from Hanoi, served by daily scheduled ferries and barges. Most journeys are a road leg to a port followed by a crossing, which is why the coach platforms in sleeper buses in Vietnam are the practical starting point.
How the neighbouring bay works, including what the World Heritage listing covers, is in Ha Long Bay. The northern seasons, which decide whether the bay is clear or grey, are in when to go to Vietnam. Coverage drops once you are out among the islands, so size your plan before you sail: how much mobile data for Vietnam and the plans in the Vietnam eSIM store.