Underneath Sagada is a network of limestone caves and subterranean streams. These caves were created by water eroding whole limestone mountains over a period spanning thousands of years. Some caves are dry, as if the underground rivers that have created them disappeared. However, these caves are dry simply because the water has found another channel by seeping through the mountain and emptying through numerous small watery caves.

SUMAGING, aptly nicknamed as the Big Cave, was created by water erosion. Guides equipped with lanterns and ropes are necessary companions for exploring this cave as well as other big caves found in Southern Sagada. Visitors never fail to be awed by Sumaging's sheer size, fascinating chambers and rock formations, some of which are dubbed as the "King's Curtain", "Rice Granary", "Cauliflower", "Dancing Hall", etc...; all for their larger than life resemblances of the real things. A part of Sumaging known as "The Tunnel" consists of a series of tiny passages requiring limbo-like movements (read as c-r-a-w-l-i-n-g) to pass through.

During pre-Christian Sagada, these caves served as burial grounds for the locals. With the dead poised in the fetal position encased in a coffin carved out of enormous pine tree trunks, Sagada Igorots of yore may have though these caves to provide the final touch in resembling the environment of a mother's womb... a suitable final resting place.