World's Longest Navigable Underground River (Former Record)

The Puerto Princesa Subterranean River in Palawan carries boats about 4.3 kilometers through an 8.2-kilometer underground stretch of the Cabayugan River within a cave system at least 32 kilometers long. It was considered the world's longest navigable underground river until a longer one was found in Mexico, and it was named one of the New7Wonders of Nature in 2012.