Hanoi Ha Long Bay is located about 3 hours east of Hanoi and is a UNESCO World Heritage Site. It is also one of the most popular tourist destinations in Vietnam. It is home to Jade Green Water and approximately 2000 small islands, most of which are made of limestone. You can go on a one-day trip to Halong Bay, but in my opinion, it is best enjoyed on an overnight cruise. If you have spent enough time in Hanoi, then a boat tour in Halong Bay is a must.