If you are travelling in Vietnam with time limitation, air travel is your best domestic option. You can also take advantage of it when traveling between extended distances down Vietnam's length - especially the routes between Hanoi and Hue, Da Nang and Nha Trang, or Nha Trang and Ho Chi Minh City.
Vietnam's air-conditioned trains are safe, comfortable and inexpensive, the ideal way for independent travelers to get around and see Vietnam at ground level. Country trains offer a journey along the country (from Hanoi to Saigon and vice versa) with panorama views of sceneries / landscapes. You can get a real insight into Vietnam of both urban and rural when you travel by train. SE1 and SE3 Express Train are two main daily trains with the best quality that cover 4 main stations: Hanoi - Hue - Danang - Nha Trang - Saigon.