Ha Long Bay is Vietnam's most recognised natural landmark - a UNESCO World Heritage Site covering 1,553 square kilometres of the Gulf of Tonkin, dotted with 1,969 limestone karst islands rising from green-grey water. The name means 'descending dragon bay,' from a legend that a dragon mother and her children descended into the sea and formed the islands. The bay's core zone holds the main attractions: Sung Sot Cave, Ti Top Island, Cửa Vạn floating village, and countless channels and lagoons.
Northeast of the core zone lies Bái Tử Long Bay; south lies Lan Hà Bay and Cát Bà Island - all three share the same karst landscape. Ha Long is the most visited of the three; Lan Hà Bay offers a near-identical experience with significantly fewer boats.