It depends entirely on your point of departure.
See Communist Vietnam website.
Not long if you are in Cambodia and have a passport.
2 mins
9 hours
99 hours
5 hours
3-7 days
10 days
19 years, 180 days
how long does it take to travel by boat from vitnarm to australia
1 to 2 weeks
It takes approximately from 8 to 15 days to mail a letter from Vietnam to US. However, it would take 3 days if you used FedEx.