There is a Vietnam VISA exemption policy for all nationalities to visit Phu Quoc Island. Since 2005, Phu Quoc Island has been classified as a Special Economic Zone and foreigners are eligible for a 30-day VISA exemption. Visa exemption’s requirement for Phu Quoc island:

• Your passport must not expire within 6 months counted from the date of your arrival in Phu Quoc Island.
• You have a ticket to leave Phu Quoc Island to an international destination within 30 days from the day you arrived, whether via a cruise ship or a flight (that means you don’t have to fly directly to Phu Quoc but transit through one of Vietnam International Airports provided that Phu Quoc is your final destination).
• You will leave Phu Quoc Island within 30 days and the onward destination is not within Vietnam territory.
• You must not be on INTERPOL’s wanted persons’ list nor haven’t been previously extradited from Vietnam

This exemption does not accept in anywhere else within Vietnam territory, so you will have to issue a Vietnam VISA to visit other destinations in Vietnam except Phu Quoc Island. If you want to combine Phu Quoc Island with other destinations in Vietnam, you should apply a visa to adapt the period of time you visit the “other destinations”. You can visit Phu Quoc with a free visa, then come to these destinations first with a visa. But don’t visit these destinations first with a visa and then coming to Phu Quoc, because if you do like this, you are not allowed to use visa exemption in Phu Quoc. Phu Quoc visa exemption is only applicable for those using international flights to this island. If you use a transit flight to Phu Quoc, make sure the transit airport is not in Vietnam. If so, you have to leave from international terminal to domestic terminal and you are required to have a visa.