How deep is a black hole?

When it comes to black holes, depth is meaningless because, by definition, all black holes disrupt the space-time continuum. This is why the concept of depth only applies to objects like planets and stars.

Initially, there exists an observable boundary known as the "even horizon" beyond which light cannot break free from the immense force of gravity.

Nobody knows what lies beyond that point, though some people think it might be a "singularity," which is the point at which time and space stop existing. The big bang itself originated at a singularity.

Therefore, inside a black hole, the three-dimensional universe we live in might very well transform into a single dimension or into nothing at all. We are just not sure.

Black holes are defined by their mass, size, and angular momentum; however, the concept of depth does not apply to them in the same way that it does to physical objects.