SM UB-89 was a German Type UB III submarine or U-boat in the German Imperial Navy () during World War I. She was commissioned into the German Imperial Navy on 25 February 1918 as SM UB-89. UB-89 was lost in a collision with the light cruiser SMS Frankfurt in Kiel. Seven crew members perished in the accident. On 30 October 1918 the boat was raised by the salvage ship SMS Cyclop. On 7 March 1919, en route to surrender, UB-89 began to drift and was towed to Ymuiden. In 1920, the boat was broken up in Dortrecht