The island of Palawan, the fifth largest of the Philippines archipelago, is home to an extraordinary natural treasure, one of the underground wonders of our planet. The Puerto Princesa Underground River was once named after the mountain of Saint Paul, that covers the whole length of the river, and it is known by local people as Natuturingan Cave. It is located on the western coast of the island, 50 kilometres north-west of the capital, Puerto Princesa.

Mount Saint Paul is just over 1,000 metres high, the karst area is fairly limited, yet the caves that runs through it over three dimensions is tens of kilometres long, and is today the longest cave of the archipelago.

The cave and the surrounding area became a national park in 1971, and in 1999 it was declared a UNESCO World Heritage Site. In 2012 it was included on the list of the "New7Wonders of Nature".

In its chambers immersed in the silence of time are delicate mineralisations and speleothems of moving beauty, true treasures of crystal: some very rare, others even unique in the world. The underground river is indeed an extraordinary place in many respects: biology, mineralogy, hydrodynamics. And it is simply beautiful.

The extraordinary body of photographs produced by La Venta during the explorations along the Puerto Princesa Underground River is the absolute protagonist of this book, which is accompanied by narrative and scientific texts that will guide the reader through this wondrous discovery.