UB-46 was a Type UB II submarine built by AG Weser (Bremen) for the German Imperial Navy, commissioned 12 June 1916.
During World War I operated in the Black Seas, and was sunk by a russian mine in December 1916.
According to information Wikipedia:
A 16 metres (52 ft) portion of the wreck comprising the forward section of the torpedo room and battery compartment was located in 1993 during coal extraction operations and was salvaged by the Turkish navy;
the remainder of the vessel could not be located. She was put on display in an outdoor exhibit at the Turkish Naval Museum in Istanbul