Da Nang or Ha Long?

This is where the two differ most. Da Nang's beach runs almost unbroken from Son Tra down towards Hoi An, wide and pale with room for everyone, and it is a beach you swim from every morning. The catch is the autumn monsoon, when red flags go up.

Ha Long's Bai Chay beach is made of imported sand, and the water is shallow and often murky. The best swimming there is off a cruise boat or on a small island such as Ti Top, while the clean sand of Quan Lan needs an overnight trip.

Both cities do excellent seafood straight from the tank, but Da Nang has far more besides. Its spicy central cooking includes mi quang, banh xeo and pork rolled at the table, it has busy food halls in Han and Con markets, and its coffee culture takes the strong iced brew seriously.

Ha Long's best dish is cha muc, its springy squid cakes, followed by northern breakfasts of pho and banh cuon in the backstreets. Beyond that, you are mostly left with cruise set menus and large tourist restaurants.

Neither city is a heritage destination in its own right, but Da Nang has more to see. The Museum of Cham Sculpture holds the world's finest collection of Cham carving, and the cave pagodas of the Marble Mountains are worth half a day.

Ha Long's offering is the Quang Ninh Museum, a striking black glass building, along with Long Tien pagoda and the floating fishing village of Cua Van out on the bay. Most visitors get through all of it in an afternoon.

Da Nang has the livelier evenings. People walk along the Han River as the bridges light up, eat at open-air beer halls, and fill the craft beer bars and late pubs of An Thuong behind the beach. There are a few clubs as well.

In Ha Long, evenings mean karaoke and seafood in Bai Chay, or squid fishing off the stern of a cruise boat followed by an early night.

Ha Long has the more remarkable landscape. Its bay is a world-class seascape of forested karst towers, caves such as Sung Sot and enclosed lagoons reached by kayak. Cat Ba adds national park trails and rock climbing.

Da Nang's nature is more varied and close to the city. You can watch for douc langurs on Son Tra, ride over the Hai Van Pass, walk the rainforest of Bach Ma, snorkel at the Cham Islands and surf in winter. It is very good, but nothing there matches the bay.

Da Nang's location is a major advantage. Hoi An's lantern-lit old town is under an hour away, and the brick temples of My Son and the imperial city of Hue each make a full but rewarding day.

From Ha Long, the best outing is the holy mountain of Yen Tu, with its pagodas climbing through old forest. Hai Phong and the Bach Dang battlefield are near too, but Hanoi is too far for comfortable day trips.

Da Nang is slightly the easier choice with children, mainly because of the long beach, resort pools and kids' clubs, and the Ba Na Hills cable car with its Golden Bridge and indoor amusement park.

In Ha Long, the adventure is the cruise itself: caves, kayaks and jumping off the deck, plus the Sun World rides on shore. Overnight boats suit older children better than toddlers, and it is worth checking the railings on cheaper vessels.

Neither city has a metro, and in both you will rely on cheap taxis booked through an app. Da Nang is a little more manageable: the river centre and the beach are a short ride apart, the coastal road to Hoi An is straight and flat, and cycling is possible.

Ha Long is spread out in two halves on either side of the Bai Chay bridge, and pavements are patchy once you leave the waterfront. Getting there from Hanoi means a long transfer by road.

Da Nang gives you things to bring home that are made nearby. The Non Nuoc workshops below the Marble Mountains carve everything from small figurines to life-size statues, Han and Con markets sell coffee and fabrics, and the tailors and lantern makers of Hoi An are a short ride away. For everyday shopping there are modern malls.

Ha Long has much less to browse. There is the Bai Chay night market, a few pearl showrooms by the bay and a bag of dried squid from Hon Gai market, and that is about it.

On land, both cities are very cheap. Street food, hotels near the water and taxis all cost very little in either place. The difference is in where the big expense falls.

In Da Nang, costs only rise if you choose the beachfront resorts or Ba Na Hills, so a long stay can stay modest. In Ha Long, the overnight cruise is the main cost of almost every visit, and boats range from basic to genuinely luxurious.

Neither city is a place to plan evenings around a stage, but Da Nang gives you more to catch. With some luck you might see tuong, central Vietnam's classical drama of painted faces and pounding drums, though shows are occasional and played to a local audience. In summer, international fireworks light up the sky over the Han River. An evening in Hoi An adds bai choi singing games in the old town and large staged shows on the river.

Ha Long has almost nothing with a programme of its own. A performance there usually means a staged show at the Bai Chay entertainment complex or folk songs on board a cruise. If a night of music or theatre matters to you, plan it around Da Nang and Hoi An, and spend Ha Long's evenings on the water.

Da Nang is easier to relax in day to day. There are massage parlours on almost every street near the beach, spa villas over the sea on Son Tra, and a slow rhythm of dawn swims and long coffees.

In Ha Long, the calm is found out on the water, with tai chi on the sundeck and a quiet night anchored among the karsts. On land, the town is noisy. Its real bathing option is the large mineral-spring onsen at Quang Hanh, which feels more authentic than Da Nang's hot springs park.