  The mass of an AdS black hole represents its enthalpy, which in addition to
internal energy, generally includes the energy required to assemble the system
in its environment. In this paper, we consider black holes immersed in a more
complex environment, generated by a scalar field with an exponential potential.
In the analogue of the AdS vacuum, which we call dilaton-AdS, the scalar field
has non-trivial behavior, breaking the hyperscaling symmetry of AdS and
modifying the asymptotic form of the spacetime. We find that the scalar field
falloff at infinity makes novel contributions to the ADM mass and spatial
tensions of dilaton-AdS black holes. We derive a first law and Smarr formula
for planar dilaton-AdS black holes. We study the analogue of thermodynamic
volume in this system and show that the mass of a black hole again represents
its enthalpy.

General Relativity and Quantum Cosmology;High Energy Physics - Theory