Fodor's Expert Review Tha Kaek
Parts of the ancient city wall in this port in Khammuan Province are still intact. Stunning countryside and karst (limestone caverns and sinkholes) surround Tha Kaek, and the area contains dramatic limestone caves, most notably Tham Khong Lor. More than 6½ km (4 miles) long, this cave is so large that the Nam Hin Bun River runs through it. Thailand's provincial capital of Nakhon Phanom sits across the Mekong River from Tha Kaek. Ferries connect the two cities.