Since it was listed as a World Heritage Site in 2014, this exceptional collection of karst landscapes has been a bit of a victim of its own success. Avoid visiting at weekends, and opt for a walk before 10am or after 4pm to avoid the queues at the ticket office and the crowds on the water. In an area of just over 6,000 hectares, more than 200 limestone peaks rise above valleys carpeted with rice paddies, topped with lush vegetation. Boat trips take you along the canals and even inside the caves at the base of the peaks.