Cát Bà, Hải Phòng · Nature
Thien Long Cave
Picture a narrow cave mouth, rock jutting out across the way, and right in front of it a tomb that the people of Phù Long say belongs to the ancient Việt. What remains from earlier times at Thiên Long Cave is not behind glass. It sits on the path you walk in by.
01What people come for
People come to take a boat through a mangrove channel and then enter a multi-chambered stalactite cave. The Phù Long area has mangroves, tidal flats and evergreen forest on limestone mountains, and lies within the Cát Bà Archipelago World Biosphere Reserve, recognised by UNESCO on 2 Dec 2004.
Getting there and around
The way in is by boat across a channel through the mangrove forest, then landing and walking a short stretch, about 400 m, to the cave mouth, usually with a local guide. The trip costs money for boat hire and a guide. It is unclear whether there is a separate admission ticket for the cave.
Before you go
A visit takes about half a day, not counting the journey there (Cát Hải special zone tourism portal). The cave mouth is fairly narrow, with rock jutting out across the way; inside you must stoop and climb over a mass of stalactite, so you need some fitness and shoes with good grip. No official source mentions lighting, railings or rescue in the cave, and there is no official notice that the cave is receiving visitors, so ask a guide in Phù Long before going. Most of Phù Long is lagoon, flooded at high tide. Hải Phòng waters have a storm season in summer and early autumn (Vietnam Maritime Search and Rescue Coordination Centre), which is when the boat crossing is easily disrupted.
What this place is
A limestone cave in a karst massif north of Phù Long village, at the north-western end of Cát Bà island. Around the massif are mangrove swamps and sea. The cave is also called động Khẩu Quy (Cát Hải special zone tourism portal). The interior is divided into three relatively separate sections, layered like a labyrinth, with many hanging stalactites and dripping water; the second section has a wide vault, and to enter the third section you must climb over a stalactite mass shaped like a large turtle. According to local tourism material, the bones of ancient people have been found in the cave, and in front of the cave mouth there is a grave believed to be that of an ancient Việt person. No archaeological report has been published.
Busy and quiet times
Suitable for small groups going with a guide, and for people who can cope with climbing and stooping in narrow passages. Not suitable for small children, older people or those who dislike physical effort (according to the tour operator Hanoi Ecotour).
The story
Thiên Long Cave: a tomb at the mouth, a boat through the mangroves
Thiên Long Cave, also called Khẩu Quy Cave or Phù Long Cave, is a limestone cave inside a karst massif (a block of limestone hills carved by water) north of Phù Long village, at the north-western tip of Cát Bà Island. Around the foot of the hill lie mangrove marshes and the sea. According to local people and travel material, the bones of people from long ago were once found inside the cave, and the tomb just in front of the entrance is believed to belong to the ancient Việt, the forebears of today's Vietnamese. Those traces belong to an earlier time. The cave itself, local accounts say, was only found by villagers around the year 2000.
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Source
The description of the cave chamber, the way in by boat through the mangrove forest, the visiting time and the traces of ancient people come from a 2021 introductory article on the Cát Bà tourism portal. This portal is run by the Cát Hải Special Zone Public Service Centre, and is also the source for the name Khẩu Quy cave and for the fact that the former Phù Long commune now belongs to Cát Hải special zone. Many other travel sites (Traveloka, vietgiaitri, dulichdaocatba, vietnambooking) copy this article, so they are not counted as separate sources. The terrain of the karst block between the lagoon and the sea, the walk of about 400 m and the need to hire a boat and a guide come from showcaves.com. The narrow cave mouth and the rock blocking the way come from Báo Diễn đàn Doanh nghiệp (Jan 2023). The mangrove forest ecosystem, the tidal flats and the lagoon flooding at high tide come from Báo Văn hoá (2018). The UNESCO recognition milestone of Cát Bà Biosphere Reserve comes from Báo Nông nghiệp và Môi trường. The storm season and the northeast-monsoon season of the bay area come from the Vietnam Maritime Search and Rescue Coordination Centre. The advice on fitness and footwear is from the tour operator Hanoi Ecotour. The sources were re-checked in Oct 2026. Rejected: Traveloka's recommended season of 'April–October' (it overlaps the storm season), the storm window 'July–October' of one aggregator page that contradicts the state sources, the measurements of the stone pillar and the chamber height (sources contradict each other, with no independent measurement), the distance of 25 or 30 km (two sources differ), and the line 'perhaps closed' from showcaves (the author's own guess, with a question mark). The coordinates of the cave mouth are not settled: OpenStreetMap and Google Maps place it about 700 m apart, both at the foot of the same mountain block.
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