Over the last 27 years, extensive and impressive river caves containing massive and richly decorated passages have been explored and mapped in the NE Indian state of Meghalaya. The caves are found in both limestone and sandstone, with the latter also holding the record in Krem Puri for the world’s longest sandstone cave. Besides their beauty, the limestone caves have also yielded scientifically important finds. Numerous new species of bats, fish and insects have been discovered during the history of the expedition, and even the most recently ratified geological period, ‘The Meghalayan Age’ has its Global Boundary Marker inside a stalagmite from Meghalaya. Together, the size, beauty and scientific relevance of the limestone and sandstone caves makes Meghalaya a very significant region for virgin exploration.