Being able to travel outside the universe would be awesome, not only for the experience of going to another universe, but also to escape ours when the second law of thermodynamics dictates that our own universe will burn out!

At this time, our understanding of black holes is understood mainly by Einstein's Theory of General Relativity, and by the mathematical solutions of Schwartzchild, Kerr, Kruskal, Szekeres, and others. As it stands, our understanding of black holes is that they have an object of zero size and infinite density at their center, known as a "singularity." Everything that falls into a standard Schwartzchild black hole, for example,is summarily crushed into the central singularity, thus there is no free ride to another universe, just certain death!

However, there are known *mathematical* solutions to how black holes behave that suggest the existance of either "safe zones" (safe as in not being sucked into the singularity, but still not safe as extreme conditions inside the black hole would still kill you) or of "white holes" that push you out the same way that a black hole pulls you in. However, there are a lot of mathematical solutions in physics that don't actually occur in reality; frictionless surfaces are one example. Also, even if the theoretical black hole is a wormhole, it would be unstable and objects of most sizes would be pulled apart trying to pass through. We also do not know whether or not General Relativity is a correct theory to describe black holes. There is a competing idea from String Theory wich describes black holes as "fuzzballs" composed of mass ripped apart at the subatomic level. If black holes are really fuzzballs, then there may be no wormholes at all; plunging into a black hole would cause you also to be torn apart at the subatomic level, and merged into the fuzzball.

There is one known possibility, though, for pass through a wormhole. If General Relativity is correct for black holes, and we can create large amounts of exotic matter (matter with negative mass), then we could open up a black hole to create a wormhole that could be passed through. However, there is no known way to do it yet, but maybe one day this could be a very real possibility that we could create exotic matter.

See the main source for this answer here.