With the exception of some rarely heard of films such as Tetsuo: The Iron Man, I have always thought of The Core and Dreamcatcher as the two worst movies I have ever seen.
Anybody remember the shitty way of them drilling to the earth? They used "Unobtainium", which got harder the as temperatures rised or some shit like that.
With that said, Volcano was bad, but it wasn't "The Core" bad.