Haiphong is a beautiful beach city which is 102 km away from Hanoi. From Luong Yen Terminal, you can buy a ticket with VND140,000/one way ($7) and enjoy the 2-hour-journey to the famed city of flamboyant flame trees, curving shoreline and delicious seafood. You can also visit Cat Ba Island from Haiphong city.
Another option is to take the train (2 hour) from Hanoi Train Station to Hai Phong. The bus, however, is faster and more convenient.