Vietnam has good eSIM coverage in its major cities and tourist corridors. The three main carriers — Viettel, Vinaphone, and Mobifone — have extensive urban networks and functional rural reach along the main tourist routes. Viettel has the widest national footprint and the strongest penetration in the northern highlands, the central coast, and the Mekong Delta. For an itinerary covering multiple regions of Vietnam, Viettel-network eSIMs are the right choice.

Airalo covers Vietnam on the Viettel or Vinaphone network depending on the plan tier, and is one of the most price-competitive options for this destination. A 7-day/1GB plan runs $3-$5; a 30-day/5GB plan sits at $10-$15. For the standard Vietnam north-to-south itinerary (Hanoi, Ha Long Bay, Da Nang, Hoi An, HCMC), these data volumes are sufficient — Wi-Fi is widely available at hotels and cafés throughout the country, and eSIM data covers the gaps (navigation on the road, messaging, booking confirmations on arrival).

Yesim covers Vietnam and is the stronger choice for travellers needing higher data volumes or extending into the northern highlands (Sa Pa, Ha Giang) where rural network coverage makes having a robust carrier selection matter more. Yesim’s Vietnam 30-day plans with 5-10GB run $15-$22, slightly more than Airalo’s equivalent but with confirmed tethering support — useful for remote workers or anyone running navigation on multiple devices. Saily covers Vietnam competently and is the right choice for existing Saily subscribers.

The local SIM case for Vietnam is genuinely compelling and worth considering. Viettel, Vinaphone, and Mobifone all sell tourist SIMs at Noi Bai and Tan Son Nhat airports for approximately VND 70,000-150,000 (£2.50-£5) with 7-30 days of data including 5-20GB. Registration requires a passport but the airport counters handle it in five minutes without the KYC delays of India or Indonesia. At these prices, a local SIM undercuts eSIM providers on raw cost by a factor of two to three. The eSIM argument in Vietnam is primarily about convenience: no airport counter, no physical card, home number stays live. If you’re not concerned about those factors, a local SIM at Noi Bai for £3 is a rational choice.

Ha Long Bay cruise coverage is worth specifying. The main bay is reachable from Hanoi (3.5 hours by road) and coverage exists at the Halong City port. On the bay itself, signal varies — you’ll have 3G-4G data while anchored near the main islands but potentially no signal in the quieter bay areas. This is the same regardless of which provider you use. Download maps and offline content the evening before departure; the cruise experience doesn’t require constant connectivity.

Phu Quoc Island has strong coverage in the main resort areas (Duong Dong town, the Long Beach strip) on both Viettel and Vinaphone networks. The southern Phu Quoc national park forests have limited signal. Ha Giang province in the far north — one of the more spectacular motorcycle loop routes in Asia — has functional Viettel coverage in the main towns (Ha Giang city, Dong Van) but dead zones in the passes between them. Download the offline map for Ha Giang loop before you start; the road is unmarked enough to need it.