The Descent (2006)

In a remote mountain range, six girlfriends meet for their yearly adventure, a caving trip into the arteries of the earth. The group makes their way through the remote cave system, enjoying the beautiful surroundings. Then, deep inside the cave, disaster strikes when their route back to the surface is blocked by a rock-fall. When they learn that no one is coming to rescue them, the group starts to splinter. Unbeknownst to them, there is also something else lurking under the earth, a race of monstrous creatures hidden from the light, evolved to live perfectly in the dark.

Official website: http://www.thedescentthemovie.com