The interacting Bose gas is a system in quantum statistical mechanics where a collective behavior emerges from the underlying many-body theory, posing interesting challenges to its rigorous mathematical description. While at temperature close to zero we have precise information on the ground state energy and the low-lying spectrum of excitations (at least in certain scaling limits), much less is known close to the critical point. In this talk I will discuss how thermal excitations can be described by Bogoliubov theory, allowing us to estimate the free energy of the Bose gas in the Gross-Pitaevskii regime. This is joint work with A. Deuchert and D. Stocker.