  In the hydrodynamic regime, field theories typically have their boost
symmetry spontaneously broken due to the presence of a thermal rest frame
although the associated Goldstone field does not acquire independent dynamics.
We show that this is not the case for Carrollian field theories where the boost
Goldstone field plays a central role. This allows us to give a first-principles
derivation of the equilibrium currents and dissipative effects of Carrollian
fluids. We also demonstrate that the limit of vanishing speed of light of
relativistic fluids is a special case of this class of Carrollian fluids. Our
results shine light on the thermodynamic properties and thermal partition
functions of Carrollian field theories.
