The Austro-Hungarian Navy or Imperial and Royal War Navy (German: kaiserliche und königliche Kriegsmarine, in short k.u.k. Kriegsmarine, Hungarian: Császári és Királyi Haditengerészet) was the naval force of Austria-Hungary. Ships of the Austro-Hungarian Navy were designated SMS, for Seiner Majestät Schiff (His Majesty's Ship). The k.u.k. Kriegsmarine came into being after the formation of Austria-Hungary in 1867, and ceased to exist in 1918 upon the Empire's defeat and subsequent collapse at the end of World War I.
Before 1867, the Imperial Austrian Navy or simply the Austrian Navy, saw action in the French Revolutionary Wars, the Napoleonic Wars, the Austrian expedition against Morocco (1829), the Second Egyptian–Ottoman War, the First and Second Wars of Italian Independence, the Second Schleswig War, and the Third War of Italian Independence. Following Austria's defeat by Prussia and Italy during the Seven Weeks' War, the Austrian Empire reformed itself into the dual monarchy of Austria-Hungary, and the navy also became the Austro-Hungarian Navy. Largely neglected by the Empire in its early years, the k.u.k. Kriegsmarine expanded along with Austro-Hungarian industrialization into one of the largest navies in the Adriatic and Mediterranean Seas. By 1914, the k.u.k. Kriegsmarine had a peacetime strength of 20,000 personnel, seeing action in the Boxer Rebellion and other conflicts before World War I.