SM UB-40 was a German Type UB II

German type UB II submarine

The UB II type submarine was a class of U-boat built during World War I by the Kaiserliche Marine. They were enlarged from the preceding type UB I and were more effective vessels. The boats were a single hull design with a 50 metre maximum diving depth and a 30-45 second diving time...

 submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

 or U-boat

U-boat

U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

 in the German Imperial Navy  during World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. The U-boat was ordered on 22 July 1915 and launched on 25 April 1916. She was commissioned into the German Imperial Navy on 18 August 1916 as SM UB-40."SM" stands for "Seiner Majestät" (His Majesty's) and combined with the U for Unterseeboot would be translated as His Majesty's Submarine. The submarine sank 100 ships in 28 patrols. UB-40 was scuttled

Scuttling

Scuttling is the act of deliberately sinking a ship by allowing water to flow into the hull.This can be achieved in several ways—valves or hatches can be opened to the sea, or holes may be ripped into the hull with brute force or with explosives...

 at Ostende during the German evacuation on 5 October 1918.

The wreck of UB-40 is located & identified by divers in the recent years.