Short answer
Carry enough dong for a couple of days, get a Vietnamese SIM or eSIM with data, drink bottled or filtered water, and save the emergency numbers 113 (police) and 115 (ambulance).
01Money and ATMs
Cat Ba Town has several ATMs from Vietnamese banks along the harbour and near the market, but there are none in the countryside, the national park or the bay. On busy summer weekends some machines run out of cash. Withdraw before you go out to Viet Hai or onto a boat, and keep a reserve.
- Limits and fees. Single withdrawals are usually capped at a few million dong, and many machines charge a fee on top of your own bank's.
- Cards. Accepted in most hotels, resorts and larger restaurants, sometimes with a 2–3 % surcharge. Small eateries, boats, rentals and ticket booths want cash.
- Notes. Polymer notes from 10,000 to 500,000 VND look similar. Keep big and small notes in separate pockets to avoid paying 500,000 instead of 50,000.
02Phone and internet
Mobile coverage is good in town and along the main road, weaker in the national park valleys and patchy out in the bay. Viettel generally has the widest coverage on the island. Buy a tourist SIM at Noi Bai airport (you will need your passport) or install an eSIM before you fly. Hotels and cafés have Wi-Fi of varying speed.
03Water, food and health
- Water. Do not drink tap water. Bottled water is cheap and many hotels offer free refills from filters.
- Seafood. Choose busy restaurants, eat shellfish cooked, and be wary of buffets that have sat out in the heat.
- Mosquitoes. Dengue occurs in northern Vietnam, mostly in the rainy season. Use repellent at dawn and dusk and sleep under a net or with air conditioning in rural stays.
- Pharmacies. Several in town sell basics, often without a prescription. For anything serious, the nearest well-equipped hospitals are in Hai Phong, at least a couple of hours away including the crossing.
- Sun and heat. The summer humidity is draining. Plan hikes for early morning and drink more than you think you need.
04Language
Hotel staff, tour desks and many restaurant owners in town speak some English; in the villages and markets it is limited. A translation app with offline Vietnamese helps. A few words go a long way:
| English | Vietnamese | Say it roughly like |
|---|---|---|
| Hello | Xin chào | sin chow |
| Thank you | Cảm ơn | gahm uhn |
| How much? | Bao nhiêu tiền? | bow nyew tyen |
| No thanks | Không, cảm ơn | kom, gahm uhn |
| Delicious | Ngon quá | ngon wah |
05Tipping and etiquette
- Tipping is not expected in restaurants, but rounding up is appreciated. Tip guides and boat crews 50,000–100,000 VND per person for a good day out.
- Bargaining is normal at the market and for private boats and rentals; fixed prices apply in shops and restaurants with menus. Keep it friendly.
- Dress Swimwear is for the beach and the boat. Cover up in town, in villages and at temples and memorials.
- Photos Ask before photographing people in the floating village or the market, and never fly a drone over homes without permission.
?Questions people ask
Are there ATMs on Cat Ba?
Yes, several in Cat Ba Town. None outside town, and they can run out of cash on busy weekends, so do not rely on the last one.
Which SIM card works best on Cat Ba?
Viettel usually has the best coverage on the island and at sea near the coast. Vinaphone and Mobifone also work in town.
Is there a hospital on Cat Ba?
There is a local medical centre for basic care. Serious injuries and illnesses are transferred to hospitals in Hai Phong.