Passing through the hatch from the engine room, the visitor would find himself staring at the ends of one of the four double-ended boilers, with its four furnaces. To the right, a hatch leads to the coal bunker. To the left is a hatch which would have lead into an identical boiler room. Between the two boiler rooms, and actually between two of the boilers, a passageway exists that would lead forward, to the opposite end of the boilers, where more furnaces existed. Using this passageway when the boilers were fired up must have been dangerous, since the passage is narrow and the surrounding boilers must have made the bulkheads very hot. A roll of the sip would throw the stoker against the heated bulkhead.
 

Overall, work in the boiler rooms was extremely uncomfortable. In addition to the tremendous heat from the furnaces, and the back-breaking work of shovelling coal, the stokers, water tenders, etc. had to deal with the roar of the steam and nearby engines, and also suffer from the coal dust that filled the air.

The boilers of the OLYMPIA are called "fire tube" boilers or "scotch" boilers. These boilers, of an older type than the type that was becoming more common, had the heated air from the funraces' fireboxes pass though tubes, which, in turn, passed through the reservior of water. The more modern "water tube" boilers had the water pass through the firebox. The fire tube boilers took more time to heat up, were more dangerous if an accident should arise (more boiling water to deal with) and weighed much more than more modern boilers.

On OLYMPIA, there were 4 double-ended boilers, and 2 single-ended boilers. Each "end" of a boiler had four furnaces each, which were used to heat the water in the boiler. This gave OLYMPIA 824 square feet of grate area and 28,298.64 square feet of heating surface.