SM UC-23
 SM UC-23 was a German Type UC II minelaying submarine or U-boat in the German Imperial Navy (German: Kaiserliche Marine) during World War I. The U-boat was ordered on 26 August 1915 and was launched on 29 February 1916. She was commissioned into the German Imperial Navy on 17 July 1916 as SM UC-23. In 17 patrols UC-23 was credited with sinking 46 ships either by torpedo or by mines laid. UC-23 was surrendered at Sevastopol on 25 November 1918 and broken up at Bizerta in August 1921.