Travel by boat

You will be missing a big part of Vietnamese life if you do not spend some time on a boat.
Halong Bay is a famous destination for one- to three-day boat trips among its scenic limestone islands. Problem is that all the boats seem to visit the same places - and with high prices and poor quality boats and service real value is hard to come by! Seafood is about the same price as Europe in some places! See Halong Bay junks
Dozens of small family-operated boats ply the river in Hue taking visitors to the imperial tombs southwest of the city. This journey is long because the boats are slow taking about 4 hours or so to make the journey in one direction.
Snorkel - fishing - lunch trips are available from Nha Trang, Hoi An, and Phu Quoc to nearby islands. In Central Vietnam North East monsoon season limits many sea boat tours during the months September - February; other parts of Vietnam seem less affected.
A 90-minute hydrofoil boat operates from Saigon to the seaside resort of Vung Tau for about 120,000 dong each way - the fastest way to reach the beach from the city.
Rivers tours are perhaps the most interesting. A day-long boat trip forms the core of almost any tour of the Mekong region. See Mekong river cruises and sampans

Source: wikitravel