S18

S18 may refer to:

Aviation

 * Forks Airport, in Clallam County, Washington, United States
 * Letov Š-18, a Czechoslovak biplane trainer
 * Rans S-18 Stinger II, an American ultralight
 * Saab 18, a Swedish bomber and reconnaissance aircraft
 * Sikorsky S-18, a Russian biplane
 * Spalinger S.18, a Swiss sailplane
 * Thorp S-18, an American homebuilt aircraft

Rail and transit

 * Forch railway, a line of the Zürich S-Bahn
 * Ichinoe Station, in Edogawa, Tokyo, Japan
 * Iyo-Ōzu Station, in Ōzu, Ehime Prefecture, Japan
 * Naruko Kita Station, in Tempaku-ku, Nagoya, Aichi Prefecture, Japan
 * Tanimachi Kyūchōme Station, in Ikutamamaemachi, Tennōji-ku, Osaka, Japan
 * Yoichi Station, in Yoichi, Hokkaido, Japan

Vessels

 * HMS Otus (S18), a submarine of the Royal Navy
 * SMS S18 (1912), a torpedo boat of the Imperial German Navy
 * USS S-18 (SS-123), a submarine of the United States Navy

Other uses

 * 40S ribosomal protein S18
 * County Route S18 (California), United States
 * S18: Handle and open container with care, a safety phrase
 * S-18 85 mm gun, a Soviet tank gun
 * S18, a postcode district in Dronfield, England