Black Hole, Object or Portal?
There should be nothing special about crossing the "event horizon" - the line beyond which light cannot escape and so, in theory at least, one might "travel into a black hole" and not be aware of any physical changes at all.

However, I suspect what you mean is what would happen if one travelled to the centre of a black hole. Here we may speculate but our current theories of physics breakdown at this "singularity" and so we cannot know - nor is it easy to think of how we might design an experiment, given our currently available technologies, to test any theory we have.