Twenty-two years married and my wife has made peace with two facts about me: I can sleep in any moving vehicle, and I keep every receipt. Paper ones. In a folder, sorted by month. So when we booked a 2 days 1 night cruise on Ha Long Bay for our anniversary — arranged from home through TGROUP, because I was not going to gamble our one big night in Vietnam on a leaflet — she said fine, but you are not allowed to talk about money on the boat. I agreed. This post is the loophole.

The van picked us up near Hanoi Old Quarter just after 8am. About three and a half hours to Tuan Chau harbour, of which I was asleep for two, so in my memory it is a ninety-minute drive. The harbour at noon is organised chaos — tenders buzzing back and forth, boats waiting offshore. Ours was the Dragon Bay one. Welcome drink at twelve, safety briefing I half heard, because the limestone had started sliding past the window and it is very hard to listen to anything while that is happening.

For context, I priced overnight cruises here for weeks before we came — they run from about US$120 to well over US$400 a head. Ours landed at the sensible end and still came with a balcony, which the accountant in me files under quiet victory. Lunch was served while we sailed into Lan Ha Bay, the quieter side of the karst — fewer boats, same absurd scenery. We passed something called Finger Islet, which does look like a finger, and several hundred islands that look like nothing else on earth.

Afternoon: the Dark and Bright cave, which you enter by bamboo boat or kayak. We took the kayak, on the theory that we are still young. I steered us into the same limestone wall twice — the second time from a different angle, which I maintain shows growth. Inside, the water goes a shade of green I do not have a word for. Then swimming off the back of the boat, in water so warm it barely counts as brave. One note from later in the evening: sun cream goes on the backs of your knees too. Nobody tells you this. Now I have.

Five o'clock is when the boat quietly becomes a different boat. Tea ceremony on deck, then happy hour — buy two get one free, a promotion I respect deeply — while the sun did its thing behind the karst. Then a cooking demonstration where the chef taught us fresh spring rolls, and I lost the rolling competition to a nine-year-old from another table. Fair play, her technique was better. The captain anchored somewhere completely still for the night, dinner arrived in more courses than I had budgeted attention for, and afterwards we tried squid fishing off the stern. Total squid caught: zero. Total complaints: also zero.

My favourite section of any ledger.

Day two starts early but earns it. At 7:30 a small boat ran us over to Tra Bau, a floating fishing village in the area where they filmed Kong: Skull Island, and we kayaked between the rafts while actual fishermen did actual work around us, very patient with tourists paddling through their commute. Back on board: checkout at 9:30, then a long brunch at ten while the boat ambled back through the karst. Van at 11:30, Hanoi hotel around three. Notes for July: it is hot, the light goes hazy by afternoon, and the drive is the drive — take the nap, that is what it is for. Also, one night out there mostly teaches you that you wanted two. That is not a complaint, more a warning about how the bay operates.

Final tally: ★★★★☆ — call it four and a half, and the missing half is mostly geography's fault for parking the bay three and a half hours from Hanoi. For what we paid against what these cruises generally go for, the sums worked out better than I expected, and I am hard to please on sums. If you are plotting an anniversary — or just want the bay without organising a single thing — do what we did and put the whole job in TGROUP's hands. They sorted the van, the boat and evidently the rose petals. Tell them what you are celebrating. I am glad I did.