There are some particularly striking natural formations on display (with the help of coloured lighting, of course) each named for what it looks like: They won't hard-sell you on the trip if you're an independent traveller (the real money is in group tours) but they'll hook you up with a motorcycle taxi driver who will take you to the cave, or you can just hire one off the street — they all know where it is.
To get here, head out of town towards Phong To and turn left along the road to Sinh Ho. Seven kilometres up, you'll find a small shack on the right selling tickets. There's a steep path across the road where you'll start the 1 km walk through the forest to the cave — takes about an hour.
The Tay Bac can help arrange transport by car or motorbike.
Here are some of the formations and their translations:
Am Duong: Yin and Yang
Chay Coi: Mortar and pestle
Cu Meo: a type of owl
Nhu Hoa: Stalagmite Flower
Ong Voi: old man elephant
Su Tu: lion
Thap Ngoc: Gem Tower
Trong Da: Stone Drum