S34 may refer to:
Aviation Blériot-SPAD S.34, a French biplane Plains Airport, in Sanders County, Montana, United States Sikorsky S-34, an American sesquiplane Skyfly S-34 Skystar, a Swiss ultralight
Naval vessels
, a torpedo boat of the Imperial German Navy
, a submarine of the United States Navy
Other uses County Route S34 (California) Sulfur-34, an isotope of sulfur