The galley, or the OLYMPIA's kitchen is in the center of the vessel, with open mess and crew area adjacent to it on either side. It was here where meals were prepared for the 380-or-so enlisted men aboard ship. The crew was broken into groups of about 20 to 24 men, which formed a "mess." Each mess appointed one man to work in the galley to aid the Chief Cook in preparing the meals for the crew. This man was often the member of the mess who had the fewest abilities to be of service elsewhere, and was derisively called a "berth deck slusher."

The present galley equipment is from the post-Manila Bay period, with most being from the first decade of the twentieth century. Still it is probably very close to what would have originally been provided aboard the vessel. All of the equipment is coal-fired or steam powered, including the large lead-lined steam kettles capable of cooking a typical navy stew for the crew. It is in this small space for the number of men who had to be served.

Overhead, a large skylight exists to allow light into the galley and which could be opened to allow the heat to escape, a concern when the large steam cooking devices and coal stoves were in operation.