Black holes are not actually holes. It's more like a point on graph type of deal. Getting too close will cause spaghettification (yes that's an actual scientific term). Also, they aren't tunnels. I think the term you may be looking for is "Worm Hole". And no, we wouldn't be able to travel through them either, well at least, probably not. And that's only [i]if[/i] they exist.