The Descent (2005)
Great film about some girls exploring caves that are virtually undiscovered. These girls have bit off more then they can chew when they find cave dwelling monsters waiting to hunt and eat them. A bit slow in the beginning but wait for it after say about mid-way. I really liked this horror movie and recommend you seeing The Descent.
Plot: A woman goes on vacation with her family and friends and her husband and her daughter encounters a tragic accident. One year later she goes hiking with her friends and they get trapped in the cave. With a lack of supply, they struggle to survive and they meet strange blood thirsty creatures.