This beautiful and isolated national park is one of Thailand’s smallest, at just 23 sq miles (59 sq km). The main trail runs beside a stream which passes through a cavern, Tham Than Lot Noi, to emerge in a thickly forested, steepsided ravine. The path continues for 8,200 ft (2,500 m), climbing steeply beside the Trai Trung falls to Tham Than Lot Yai, a limestone sinkhole, and a small Buddhist shrine. On weekday mornings you may find that you are the only visitor in this delightful spot.