Halong Bay is a UNESCO World Heritage Site that covers some 150,000 hectares. It is located on the Gulf of Tonkin in the north eastern province of Quang Ninh. Aside from its size, the most impressive thing about the bay is the 1,600 islands and islets that rise up out of the water. It is famous because its stunning limestone mountains raising up from emerald waters that formed from thousand years ago. You also can have a chance to explore amazing caves as well as the culture of Ha Long.