Ha Long or Sapa?

Ha Long at least has the sea. Bai Chay's town beach is imported sand with shallow, often cloudy water, so the better swimming is from the boats, at island stops such as Ti Top or in quiet coves. The cleanest sand is an overnight trip away on Quan Lan.

Sapa has no swimming at all, only cold mountain streams and waterfalls. Anyone combining the two should treat Ha Long as the coastal part of the trip.

Ha Long eats better, mainly because of its seafood. In the halls of Hon Gai and Bai Chay you choose crabs, mantis shrimp and clams from the tanks, and the springy cha muc squid cakes are everywhere. For breakfast there are pho and bun cha in the backstreets.

Sapa's cooking is mountain food for cold evenings: salmon and sturgeon hotpots, skewers from the grills by the lake and Hmong dishes such as thang co. Beyond those, the centre relies on travellers' cafés of uneven quality. Neither town has much wine or fine dining.

Neither town has many sights of its own, so the difference is in where the interest lies. In Ha Long it is a museum and a seascape: the black glass Quang Ninh Museum, with its sections on mining and the sea, and floating fishing villages such as Cua Van out on the bay.

In Sapa it is the people who live there. Walking to Black Hmong, Red Dao and Tay villages, past indigo dyeing and wooden houses, is the cultural experience. It is best further from town, where the villages feel less staged.

Ha Long has the fuller evening. Bai Chay has beer halls, karaoke and seafood dinners, a night market and a few waterfront bars, though most of it winds down before midnight, and cruise passengers make do with squid fishing off the stern.

Sapa is quieter still: a hotpot, a drink by the fire and bed before the next walk. A handful of travellers' bars and the lakeside grills are the only late life.

Both are among Vietnam's great landscapes, and the choice is between seeing one from a boat and walking through the other. In Ha Long, limestone towers rise straight from the sea, and you explore them by cruise boat, kayak and caves such as Sung Sot, with Cat Ba adding trails and rock climbing.

Sapa's scenery is steep and farmed: terraces stepping down the Muong Hoa valley, bamboo forest, waterfalls near the Tram Ton Pass and Fansipan at 3,143m. In Sapa the outdoors starts at the hotel door, while in Ha Long it starts at the harbour.

Ha Long has more within a day's reach. Yen Tu, the forested Zen mountain of pagodas and stupas, is about an hour inland, the colonial port of Hai Phong is a similar drive, and the Bach Dang battlefield is close by.

From Sapa the standout is Bac Ha's Sunday market, about two hours away, with smaller hill markets on other days. Beyond those, most outings are simply more mountains, and Lao Cai below is a border town rather than a sight.

Ha Long is the more natural choice for families. Children get boats, caves, kayaks and swimming off the deck, and Bai Chay adds a cable car, a Ferris wheel and a water park. Summer heat and traffic need managing, and overnight cruises suit older children better than toddlers.

Sapa works for children who are old enough to walk: short treks, buffalo in the paddies and a homestay can stay with them. With toddlers it is hard going, because of the steep streets, the mud, cold rooms in winter and persistent vendors, and there is almost nothing built for children.

Getting around is equally awkward in both, for different reasons. Ha Long stretches along the bay in two halves joined by a long bridge, so beyond the Bai Chay waterfront visitors rely on cheap taxis and ride-hailing, plus cruise transfers to Tuan Chau.

Sapa's centre is compact but steep, and everything beyond it means trails, a car with driver or a motorbike taxi. Sapa is also further from Hanoi, five to six hours by road or an overnight train to Lao Cai, while Ha Long is a shorter run on the expressway.

Sapa gives you more reason to browse, thanks to the handwork of the Hmong and Dao: indigo-dyed cloth, batik, brocade and silver. The best places to find it are markets such as Bac Ha's, though machine-made copies are common and sellers can be pushy.

Ha Long's shopping comes down to pearls, night-market souvenirs and the dried squid and fish sauce of Ha Long market. Most of it is food rather than anything made by hand.

Both are very cheap once you are there, and the difference is where the big cost falls. In Ha Long it is the overnight cruise, which ranges from basic to luxurious, while hotels, taxis and street food stay inexpensive. Agree the weight and price of any seafood before it is cooked.

In Sapa the one big expense is the Fansipan cable car. Otherwise homestays, hotpot and guided treks cost little, and bargaining is expected at craft stalls.

Neither town has a theatre or concert hall, so this should not decide your trip. Ha Long's performances are staged shows in the Bai Chay entertainment complex and folk singing on some boats. Sapa's are short pan-pipe and dance displays by Hmong and Dao performers on the town square at weekends, simpler but rooted in the communities around it.

Ha Long has the edge for rest, mainly because of the water: a slow day among the karsts and a quiet night anchored in a cove. There are spas on the better boats and in the resort hotels, and mineral springs feed an onsen resort at Quang Hanh, about forty minutes east.

Sapa's answer is the Red Dao herbal bath, a hot soak in water steeped with forest plants that suits tired legs after trekking, and a homestay in the valleys is genuinely peaceful. Both towns are noisy, so in either place the calm is found outside them.