Southeast Asia Circuit eSIM Guide (2026)

The classic Southeast Asia loop covers Bangkok, Chiang Mai, Hanoi, Ho Chi Minh City, Siem Reap, and Bali across 28 days. Most backpackers follow this route in either direction.

Route connectivity analysis (5 legs, 28 days):

• Bangkok to Chiang Mai: 1h20m to 12h by overnight train (12h) or domestic flight (1h20m). The sleeper train has no WiFi. Download entertainment and maps before boarding. Your eSIM reconnects at Chiang Mai station.

• Chiang Mai to Hanoi: 2h direct by flight via Bangkok or direct (2h). Border crossing requires switching eSIM profiles. If using a regional bundle, the carrier switch happens automatically at Noi Bai Airport.

• Hanoi to Ho Chi Minh City: 2h to 34h by domestic flight (2h) or Reunification Express train (34h). The Reunification Express passes through areas with intermittent signal. Download offline maps for the Hue and Da Nang stops along the way.

• Ho Chi Minh City to Siem Reap: 3h to 12h by bus (12h) or flight via Phnom Penh (3h total). The Cambodia border crossing at Bavet/Moc Bai means switching from a Vietnam eSIM to a Cambodia eSIM. Regional bundles handle this automatically.

• Siem Reap to Bali: 5-8h by flight via Bangkok or Kuala Lumpur (5-8h with connection). Two border crossings in one day. A Discover Global or Asialink bundle avoids managing four separate country eSIMs.

Total data budget: approximately 42GB across 28 days (1.5GB/day average). Days in cities use 1.5 to 2.0GB. Transit days use 0.3 to 0.5GB. Nature and rural days use under 0.5GB. The average accounts for the mix of city, transit, and outdoor time typical of this circuit.

Airalo's Asialink bundle covers Thailand, Vietnam, Cambodia, and Indonesia on one eSIM. At 28 days and 42GB estimated use (1.5GB/day), buy the largest Asialink tier available. Alternatively, stack four single-country plans at lower per-GB rates but manage the switching yourself at each border.