These incredible images show British scientists on an expedition to map a 'never-ending' cave network in a project that dates back more than 30 years.
The twisting network of caverns underneath Gunung Mulu National Park, in Sarawak, Borneo, contains the largest cave chamber in the world, the largest cave by volume and what is believed to be the largest cave passage.
Scientists carry out bi-annual visits into several caves and have so far mapped out an incredible 186 miles of the underground network.
Using lasers and other equipment they measured the dimensions of different sections of the numerous caverns stretching throughout the UNESCO World Heritage site and feed them into a computer to build up the map.
Working with Borneo's National Parks authority, the team of Brits also began mapping the area above the caves to help tourists trekking between the cave mouths know where they are.
Making a splash: Expedition leader Tim Allen inspects the 'Shower Head' - a calcium-formed funnel which transports rain water from the surface into caves underneath Gunung Mulu National Park, in Sarawak, Borneo
Leaving a mark: Andy Eavis compares his hand size to ancient prints left in Black Hands Cave
Cavernous: Deer Cave is home to more than three million bats and is believed to be the largest cave passage in the world
Vast: The north entrance of Deer Cave - which measures nearly 390ft wide and more than 900 ft high - is just one of a network of 180miles of caverns