Yes, a very interesting factoid ... people often don't think about just how puffy the Schwarzchild radius is for the really massive black holes! The "surface" gravity on the big black holes is surprisingly low too.Chris Peterson wrote: The density a black hole can mean different things. It is possible that the center of a black hole consists of a singularity; if so, the density there is infinite, regardless of the mass of the black hole. More generally, the density of a black hole is its mass divided by the volume within its Schwarzschild radius- a value that decreases as the mass increases. The density of the black hole in 3C 348 is less than one... it would float in a big tub of water.
Of course, that's just an algebraic construct. It's quite possible that all black holes are actually finite compact objects that happen to fit inside their own Schwarzchild radius ... Perhaps there is a state of matter that is far more dense than a ball of degenerate baryons but which is still finite and in fact not a singularity.