Hall of Infinite Doors

It takes some searching, but eventually you come across another hallway traveler's discarded empty pack of mints. It's not ideal, and it's kind of gross, but it'll serve. You stand at the hole's opening and release the trash, listening for the scant few seconds it takes for you to hear a tapping. That's reassuring - you now know that no matter where that hole goes, at least it has a bottom to it.

Still, you can back out if you want.