Visa is always a concern, not only for Vietnamese people but for anyone planning to travel. Because, to reach your desired destination, the first step is often to obtain a visa (if required).
Southeast Asia
Thailand, Singapore, Laos, Cambodia, Indonesia, Malaysia have a 30-day visa exemption for ordinary passports (O.P.).
Philippines: Visa-free for O.P. holders, temporary stay not exceeding 21 days with a passport valid for at least 6 months and a round-trip or onward ticket.
Brunei: Visa-free for Vietnamese citizens with O.P. for a stay of up to 14 days.

Thailand: Visa exemption for ordinary passport holders (O.P.) with a stay not exceeding 30 days.
Singapore: Visa-free for O.P. holders, with a stay not exceeding 30 days and a round-trip or onward ticket. Financial ability to cover expenses during the stay and meet necessary conditions for onward travel is required.
Laos: Visa-free for O.P. holders with a stay not exceeding 30 days. Those wishing to stay beyond 30 days must apply for a visa in advance; the stay can be extended up to two times, each for 30 days.
Cambodia: Visa-free for O.P. holders, with a stay not exceeding 30 days.

Myanmar:
Indonesia: Vietnamese citizens (all passport types) can enter Indonesia visa-free with a stay not exceeding 30 days. The stay cannot be extended.
Malaysia: Visa exemption for individuals holding various passport types, with a stay not exceeding 30 days.
East Timor: No visa required in Vietnam. You can fly normally to their airport. There, East Timor customs will issue an entry visa for you with a fee of 30 USD. Note that you must present 100 USD for each entry. The mentioned amount is just to show, not to pay. You also need to present the round-trip air ticket.
Asia
Jeju Island (South Korea): Only visa-free when visiting Jeju Island; other places in South Korea require a regular visa. However, as there is no direct flight from Vietnam to Jeju Island, you will have to transit in another country with flights to this island.

For Vietnamese tourists with valid visas (sticker in the passport) from the United States, Canada, Japan, Australia, and New Zealand, they are allowed to travel to South Korea without a visa, only presenting the next leg of the flight.
Taiwan: Tourists from countries such as Vietnam, India, Thailand, the Philippines, and Indonesia holding valid visas and residence permits in the United States, Canada, Japan, the United Kingdom, Schengen (European Union), Australia, and New Zealand are also exempt from a visa for 30 days when arriving in Taiwan. However, online registration for approval is required, and after approval, the procedure for boarding the plane and entering Taiwan can be completed.

Kyrgyzstan: No distinction based on the purpose of entry.
North America
Panama: Vietnamese citizens entering Panama for tourism purposes are exempt from a visa and travel card.

Ecuador: The maximum duration for Vietnamese tourists visiting Ecuador is 90 days. The country unilaterally removes the visa barrier for tourists from many countries, including Vietnam.
Saint Vincent and the Grenadines: As an island nation, it does not require a visa for tourists from any country or territory. However, to enter, the Ministry of Foreign Affairs of St. Vincent and the Grenadines requires tourists to present a valid passport, a round-trip air ticket, and proof of sufficient finances for the trip.
Haiti: According to the Haitian Ministry of Foreign Affairs, only citizens of three countries: Colombia, the Dominican Republic, and Panama are required to apply for a tourist visa to enter this country. This means that citizens of the remaining countries can stay in Haiti for up to 90 days and freely explore without a visa.

Turks and Caicos: The Turks and Caicos Islands are a British Overseas Territory in the North Atlantic. Tourists only need to prove they have a round-trip flight departing the island to be allowed a 30-day stay, extendable once.
Dominica Republic: Vietnamese citizens with valid tourist visas or legal residence in the United States, Canada, and the European Union (including the United Kingdom) can travel to this country with a tourist card and a valid passport.
Costa Rica: If you have a visa (tourist, crew member, or business entry visa) valid for at least 3 months and stamped entry to the United States, Canada, Japan, South Korea, or the Schengen area, you are allowed to enter Costa Rica.
Countries/Territories with Easy Visa Access (Visa on Arrival)
Maldives: This is a visa-free country that issues visas on arrival for travelers. Just present your round-trip ticket, hotel reservation, and a passport valid for over 6 months, and the immigration officer will stamp your passport. This visa is free for 30 days.

Mauritius (officially the Republic of Mauritius) is a famous island nation for tourism located in the Indian Ocean, about 2,000 km from the African continent. Mauritius provides online visas for Vietnamese citizens. Travelers need to fill out the necessary information and apply online. Upon approval, print the visa and collect it at the border when arriving in Mauritius.
Nepal: Prepare US dollars (USD) for the visa fee (20 USD for a 15-day visa), 2 passport-sized photos matching your passport, and have a blank page to get a visa on arrival at Kathmandu Airport.
India: Vietnam is among the few countries allowed to apply for a visa directly at 4 airports in India: Delhi, Mumbai, Chennai, and Kolkata. However, the visa obtained at Indian airports is a single-entry type with a 30-day validity, priced at 60 USD.

Sri Lanka: Simply submit an online visa application, pay the visa fee with a bank card, wait for the result, print the confirmation, and bring it to the airport for departure to Sri Lanka.
United Arab Emirates (UAE): Emirates and Etihad are two UAE airlines with flights from Vietnam. Emirates flies directly to Dubai, while Etihad flies to Abu Dhabi. If using tickets from these airlines, you can easily apply for a visa online or contact their office in Ho Chi Minh City for detailed instructions. You can also purchase Stop Over packages for up to 96 hours, including a full visa package if transiting in the UAE.
Iran: Regular Vietnamese passports can obtain a 17-day visa at the Iranian border for 50 USD. Entry information in Tehran, the capital, requires you to bring passport photos for visa on arrival.

Many African countries, including Senegal, issue visas online. Travelers who register online will receive a visa application form, fill in the required information, submit it at the border, and receive a visa on arrival. The fee is 50 Euros.
Countries/Territories Granting Visa Fee Exemption
Algeria, Afghanistan, Mongolia, Nicaragua, Romania, and Cuba are countries that issue visas to Vietnamese individuals with valid passports and waive the visa fee.
As per Ione
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Reference: Travel guide on Mytour
MytourNovember 11, 2015