Halong Bay is one of 7 natural wonders in the world and a World Heritage site in Vietnam. A visit here is a must for any trip to Vietnam, with almost 2,000 islands rising from the emerald water of the Gulf of Tonkin, Halong is an excellent example of a Karst landscape and it is easy to see why it is one of the 7 natural wonders of the world. This overnight trip allows you to see all of what is best of this beautiful area.