  If a black hole (BH) is initially in an approximately pure state and it
evaporates by a unitary process, then the emitted radiation will be in a highly
quantum state. As the purifier of this radiation, the state of the BH interior
must also be in some highly quantum state. So that, within the interior region,
the mean-field approximation cannot be valid and the state of the BH cannot be
described by some semiclassical metric. On this basis, we model the state of
the BH interior as a collection of a large number of excitations that are
packed into closely spaced but single-occupancy energy levels; a sort-of "Fermi
sea" of all light-enough particles. This highly quantum state is surrounded by
a semiclassical region that lies close to the horizon and has a non-vanishing
energy density. It is shown that such a state looks like a BH from the outside
and decays via gravitational pair production in the near-horizon region at a
rate that agrees with the Hawking rate. We also consider the fate of a
classical object that has passed through to the BH interior and show that, once
it has crossed over the near-horizon threshold, the object meets its demise
extremely fast. This result cannot be attributed to a "firewall", as the trauma
to the in-falling object only begins after it has passed through the
near-horizon region and enters a region where semiclassical spacetime ends but
the energy density is still parametrically smaller than Planckian.
