S41

S41 may refer to:

Aircraft

 * Blériot-SPAD S.41, a French fighter aircraft
 * Short S.41, a British biplane floatplane
 * Sikorsky S-41, an American flying boat

Rail and transit

 * S41 (Berlin), a line of the Berlin S-Bahn
 * S41 (Long Island bus)
 * S41 (ZVV), a line of the Zürich S-Bahn

Submarines

 * ARA Santa Cruz, of the Argentine Navy
 * BRAZILIAN SUBMARINE Humaitá
 * HMS Unseen (S41), of the Royal Navy
 * INS Vagir (S41), of the Indian Navy
 * USS S-41 (SS-146), of the United States Navy

Other uses

 * New Jersey Route 73, designated Route S41 until 1953
 * S41: In case of fire and/or explosion do not breathe fumes, a safety phrase
 * Sulfur-41, an isotope of sulfur
 * Xhosa language
 * S41, a postcode district in Chesterfield, England