The Puerto Princesa Subterranean River is a UNESCO World Heritage Site located in the Philippines. This natural wonder features a 24-kilometer-long underground river that flows through a stunning limestone cave system. It is known for its impressive rock formations and diverse ecosystems, making it a popular destination for eco-tourism. Visitors can explore the river by boat, allowing them to witness the unique geological features and rich biodiversity. The area is home to various species of flora and fauna, some of which are endemic to the region. The river is also part of the Puerto Princesa Subterranean River National Park, which protects its natural beauty.