Ha Long or Krabi?

This is where the two differ most. Ha Long's Bai Chay beach is imported sand on shallow, often murky water, and the swimming is better from a cruise deck or at Ti Top island. From December to March it is too cool for most people anyway.

Krabi is built around its beaches. Railay West and Phra Nang sit beneath limestone cliffs, and Klong Muang and Tubkaek are quieter strips backed by resorts. Poda, Chicken Island and the Hong islands are a short longtail ride away, and the sea is warm all year.

Both are good places for simple, cheap seafood rather than food destinations, but the cooking is different. In Ha Long you choose crabs, mantis shrimp and sea snails from the tanks in the halls of Hon Gai and Bai Chay and have them steamed or grilled. You eat springy cha muc squid cakes, and pho or banh cuon for breakfast.

Krabi has the fire of southern Thai food: turmeric fish soups, khao mok gai and roti, shaped by its Muslim communities. The best of it is at Krabi Town's evening market, not on Ao Nang's tourist strip.

Neither is a sightseeing city, and you will run out of sights within a day in either. Ha Long has a little more to visit indoors: the black glass Quang Ninh Museum covers mining and the sea, and the floating villages such as Cua Van show how people lived on the bay.

In Krabi, the one real landmark is the Tiger Cave Temple, a climb of more than 1,200 steps to a hilltop Buddha. Krabi Town adds a few Chinese shophouses.

Krabi gives you more to do after dark, though neither place has proper clubs. Ao Nang has a run of cocktail bars and a small alley of late spots, and Railay's beach bars bring hammocks, reggae and fire-spinning. For a real party night, the ferry goes to Phi Phi.

Ha Long's evenings are local in style: beer halls, karaoke rooms and seafood dinners in Bai Chay, mostly winding down well before midnight. On a cruise, the night's entertainment is squid fishing off the stern.

Both have the same kind of drowned limestone landscape, and both are superb, but you experience them in different ways. Ha Long Bay is the larger seascape, close to two thousand forested islets, explored by boat. You visit caves such as Sung Sot and paddle under arches into hidden lagoons. Lan Ha and Bai Tu Long bays are quieter alternatives.

Krabi lets you get onto the rock and into the forest. Railay and Tonsai are world-class sport-climbing crags, the Ao Thalane mangroves are made for kayaking, and inland there are the Emerald Pool and the Dragon Crest hike. Snorkelling and diving around the outer islands are an extra Ha Long cannot match.

The outings are about level, but they differ in kind. From Ha Long the best trips are on land and into history. Yen Tu, the holy mountain of Vietnamese Zen, is about an hour inland, with pagodas climbing through old forest. Hai Phong has French colonial streets, and the Bach Dang battlefield is close by.

From Krabi almost everything goes by boat: Phi Phi, the quiet villages of Koh Yao Noi, and Koh Lanta's stilted Old Town. Phuket's Sino-Portuguese quarter is a long day out.

Children enjoy both, for different reasons. Ha Long has built attractions that Krabi lacks: Sun World's cable car over the water, the giant Ferris wheel and the water park. A cruise with caves and kayaking feels like an adventure, though overnight boats suit older children better than toddlers.

Krabi's appeal is the shallow, warm water of the dry season at Klong Muang and Phra Nang, plus resort kids' clubs. In both places, open boats, strong sun and traffic need care with small children.

In both, you walk the waterfront and take cheap taxis or ride-hailing cars for anything further. Ha Long is stretched out in two halves, Bai Chay and Hon Gai, joined by a long bridge. Cruise transfers usually take care of getting to the harbours.

Krabi uses shared songthaew pickups between Ao Nang, the northern beaches and Krabi Town. Railay has no road, so getting there depends on longtail boats that stop running in heavy seas.

Neither is worth a trip for shopping, and both come down to souvenirs from markets. Ha Long's best buys are cultured pearls and a bag of dried squid from Ha Long market. Krabi has beachwear stalls and tailors in Ao Nang, and handmade bits at Krabi Town's weekend walking-street market.

Ha Long is the cheaper of the two once you are on land. Bai Chay hotels, street food and market seafood cost very little, and the overnight cruise is the one big expense, with boats ranging from basic to luxurious.

Krabi is still good value, especially in Krabi Town. Costs climb in Ao Nang and on roadless Railay, though, and island tours, longtail fares and national park fees for foreigners add up over a longer stay.

There is little to see live in either. Ha Long has staged shows at the Bai Chay entertainment complex and folk singing on some cruise boats. Krabi offers beach fire-spinning, bar cover bands and Muay Thai fights put on for visitors near Ao Nang.

Krabi makes slowing down much easier. Thai massage shops are everywhere, the resorts at Tubkaek and Railay have open-air spa pavilions, and yoga is easy to find. At Khlong Thom, warm mineral water runs over limestone into pools in the forest.

In Ha Long the calm is mostly on the boat, with tai chi at dawn and nights anchored in a sheltered cove. Bai Chay itself is loud with motorbikes, but the Quang Hanh onsen resort is close by.