Thien Canh Son Cave on a Bai Tu Long cruise

Thien Canh Son is a short climb to a small cave. About seventy stone steps lead up through trees to a narrow entrance, the chamber behind it is low and hung with yellow-brown stalactites, and a white-sand beach curls round the foot of the island. Thirteen of the 15 Bai Tu Long boats we publish stop there on their one-night trip, counted from their timetables on 22 October 2026: six on the first afternoon, seven the next morning. The other two go on a two-night trip, so all fifteen have the cave on their stop lists.

If you are choosing between boats on this bay, the cave will almost certainly be on your trip. What changes is the hour, and what the boat does with the rest of the stop.

Where is Thien Canh Son, and what is inside?

It is on Hon Co, an island about 14 km from Ha Long International Cruise Port and 19 km from Tuan Chau, and the Ha Long Bay and Yen Tu heritage management board files it under its plainer name, Co Cave. The board says the name Thien Canh Son comes from scenery likened to a fairyland. Operators sell this water as Bai Tu Long. The board places the cave inside the Ha Long Bay World Heritage area, on the sightseeing route it numbers VHL4, together with Vung Vieng and the overnight anchorage at Cong Do.

The board describes a small cave about 40 metres above the sea, with a low roof and a tight way in. Past the entrance, the stalactites hang from the ceiling, and a passage at the far end lets in daylight and a view back over the islands. Here, the board adds, you can also kayak among the surrounding limestone islets.

The cave receives visitors 07:30 to 17:00 from 16 April to 31 October and 08:00 to 16:45 from 1 November to 15 April, on the board’s visiting-hours page, updated in November 2024. Its fee page, updated in March 2025, prices a route VHL4 ticket with one night at the Cong Do anchorage at 500,000 VND a person.

Which Bai Tu Long boats stop at the cave?

Thirteen of the 15 Bai Tu Long boats we publish stop at the cave on their one-night trip, six on the first afternoon and seven on the second morning, and on every one of them you walk up the steps. The times are the operators’ own, from each boat’s timetable; Renea, Signature and Swan put the cave on the second morning before check-out. Entrance fees are shown as each operator’s terms state them.

Boat	When	What follows at the stop	Entrance fees in the operator’s terms
Dragon Legend	Day one, 14:30	Kayaking from 15:00	Included
Dragon’s Pearl	Day one, 14:30	Kayaking from 15:00	Included
Prince	Day one, 14:30	Kayaking from 15:00	Ask when booking
Emperor	Day one, about 15:00	Kayaking	Included
Paloma	Day one, 15:15	Kayaking, both done by 15:40	Included
La Regina Classic	Day one, 15:30	Happy hour on deck at 17:30	Included
Athena Royal	Day two, 07:30	The beach below	Ask when booking
Larissa	Day two, 07:30	Cabins cleared by 09:15	Included
Red Dragon	Day two, 07:45	Kayaking near Cong Do at 08:15	Ask when booking
Cycad	Day two, 08:00	Cabins cleared at 09:30	Ask when booking
Renea	Day two, morning	Spring-roll class, then brunch	Ask when booking
Signature	Day two, morning	The white-sand beach below	Included
Swan	Day two, morning	Packing; ashore by 11:15	Included

The other two Bai Tu Long boats reach it on longer trips. Treasure sends a transfer boat to the cave on the middle day of its two-night programme, and Violet sails only a two-night route, with the cave on it. Two Ha Long boats, Athena Premium and Calista, also bring three-day guests here by day boat, at 10:00 on the middle day.

How steep is the climb?

Steep enough to need proper shoes. The board counts about seventy stone steps to the cave mouth, which sits roughly 40 metres above the water. La Regina Classic’s timetable tells guests to wear trainers for the climb, and Cycad’s operator asks for sports shoes and a camera.

Guests on these boats mention a cave visit often and say little about the climb. A guest on La Regina Classic, reviewing in October 2025, called it hiking to Thien Canh Son Cave and found the view beautiful and relaxing, while a Renea guest reviewing in December 2025 listed “a short hike” among the included activities. A French guest on Renea, reviewing in August 2026, found the cave visit pleasant, if one they could have skipped.

The limitation is the entrance. On the board’s description the way in is narrow and the ceiling low, so a guest who dislikes tight spaces, or who cannot manage seventy stone steps, should plan to stay on the beach or aboard.

Is the morning visit better than the afternoon one?

Neither is better for the cave itself; the difference is what comes with it. Six of the thirteen go on the first afternoon, between 14:30 and 15:30, and five of those put the kayaks in the water straight after the cave, so one stop covers the climb and the paddle. La Regina Classic is the exception: its cave visit is at 15:30, and its kayak option comes at Vung Vieng at 07:45 the next morning. All six afternoon boats go round Vung Vieng fishing village the next morning, and Cycad does the two the other way round, so on the one-night Bai Tu Long trip seven boats give you both: Cycad, Dragon Legend, Dragon’s Pearl, Emperor, La Regina Classic, Paloma and Prince.

The seven morning boats fit the cave in before check-out. Athena Royal and Signature pair it with the beach. The catch is the clock in winter. From 1 November to 15 April the board opens the cave at 08:00, and three of the four morning boats that print a time put it earlier, at 07:30 or 07:45, so ask the crew whether the visit moves in those months.

Which boat should I book for the cave?

For the cave and a strong guest record, Renea. It has 259 reviews collected over more than three years, 89% of them five-star, counted on 22 October 2026, and it goes up on the second morning of the one-night trip, or the last morning of the two-night trip. Swan, with 239 reviews, is the only other Bai Tu Long boat past 100 and keeps the same pattern. Our guide to Bai Tu Long cruises compares the rest of the bay’s boats, the quietest bay sets out why we rate this water the quietest, and the caves and islands guide puts Thien Canh Son beside the other stops.

Common questions

Is Thien Canh Son in Ha Long Bay or Bai Tu Long? Both names are used for the same water. The management board puts the cave inside the Ha Long Bay World Heritage area, on its route VHL4, and every Bai Tu Long boat that goes there sells the trip under the Bai Tu Long name. You will not find it on a Ha Long-side two-day cruise. Of the 31 Ha Long boats we publish, Athena Premium and Calista reach it on a three-day trip and Au Co on a four-day one.

Can I see it on a day trip? Yes. La Muse, a 36-guest day boat run by Indochina Junk, leaves Ha Long International Cruise Port at 12:00 for a five-and-a-half-hour afternoon with the cave and kayaking, on the operator’s page read on 16 October 2026. Bhaya’s private day boat lists it among the options for its six-hour trip.

Is it suitable for children? For children who can walk seventy steps, yes. The cave is small, about 40 metres above the sea on the board’s figures, and the way in is narrow under a low roof, so a child who is wary of tight spaces may want to wait on the beach with one adult. The visit is short; on Paloma’s timetable the cave and the kayaking together take 25 minutes. Carry water, and keep small children close on the steps.