I saw The Descent, The Cave and The Cavern. Almost same story. The Descent and The Cave is pretty ok to me. The Cavern is the worst of the three.
I haven't seen the last one. I think I need to see it, as it was shot in Kazakhstan.
My comparison:
1. The Descent:
Location - Appalachian Mountains, North Carolina, USA
Explorers - 6 to 7, all American.
Attackers (mutants): several dozen, origin unknown
2. The Cave:
Location - Carpathian Mountains, Romania
Explorers - 7 to 8, mostly American.
Attackers (mutants): several dozen, origin unknown
3. The Cavern:
Location - Kyzyl Kum Desert, Kazakhstan.
Explorers - 7 of them. 5 foreigners and two natives
Attackers (mutants): Single attacker, survivor of the plane crash.
Can not believe enough people like this sort to warrant so many of these films
Have not seen a decent horror movie for some time, will try to find one.