This is what I found @ VietnamImmigration.com. I have no intentions on using them. I was just doing some research until I hear from Vietnam e-Visa hopefully on Monday or Tuesday…
If the cruise stops in different cities in Vietnam, does this count as many visits? Numerous cruises along the coast of Vietnam visit several ports. If you visit numerous cities in Vietnam, would this be considered a single entry or many entries? How may several visas be applied for if there are many entries?
In truth, if a cruise ship cruises from one Vietnamese port to another, only one visit is counted. The entrance port will be the first port of entry, while the departure port will be the last port of visit. You are not required to apply for a multiple-entry visa. In this instance, the single-entry E-visa will suffice.