Train
Vietnamese trains are the ideal way to get around and experience Vietnam at ground level.  The trains are safe, comfortable and inexpensive.  Trains link Hanoi, Hue - Danang, Nha Trang, and Saigon (Ho Chi Minh City).  Hoi An has no station, but it's just 30km by bus or taxi from Danang.  There are also trains from Hanoi to Haiphong (for Halong Bay) and Hanoi to Lao Cai (for Sapa). In case you were wondering, Ho Chi Minh City (HCMC) is the name for the whole conurbation.  The city centre is still called Saigon, and it is 'Sai Gon' (and not Ho Chi Minh City) which appears in the railway timetables and in big letters on Saigon station building.
 
There is some wonderful scenery between Hanoi and Saigon. Between Hue and Danang is the most scenic section of line, running along the coast past bays and islands and through the hills.  The train travels at low speed up the fierce gradients, with an assisting locomotive at the rear and people sitting on the roof..!
  
Trains SE1 to SE6.
These are the best trains in Vietnam, equipped with modern air-conditioned coaches.