What to note before having a holidays to Halong bay Vietnam?

Halong bay is the most spectacular bay of Vietnam. Located in the gulf of Tonkin, just about 180km from Hanoi city, Halong is one of the most famous tourist destinations to all travelers.
The amazing beauty of nature with over 2000 limestone islands & islets, a series of hidden caves and beaches, the deep emerald green water, calm waves,... making Halong so attractive and the best place for having a cruise tour.