We tiptoed one-by-one down narrow wooden stairs. I sometimes had to stoop through the contracted passageways. I snapped photos of the frozen waterfalls, and spikes of ice trickle from the ceiling or rise from the ground.

Some are too large for a person to wrap their arms around. Others are thin as needles.

Polychromatic lights cast them with otherworldly hues.

It takes about 15 minutes to explore the cavern, which remains frozen year-round. It's said to be the largest of its kind in China, at just over 100 meters deep and 40 meters across at its widest. It's located 2,300 meters above sea level.

The cave is believed to hail from an ice age 3 million years ago. Experts are still trying to figure out how its ice has survived.