Halong Bay is one of the heritage sites, so I think it’s the main reason why it is so famous. But indeed, Halong Bay is really beautiful with the 100% natural caves that you may not find anywhere else in this world. I believe this unique is a big attribution to the fame of Halong Bay. Besides, the seafood there is also super fresh and not really expensive when compared to the view and quality. So if you come to Vietnam, don’t forget to check it.