HMHS Britannic (/brɪˈtænɪk/) was the third vessel of the White Star Line's Olympic class of steamships and the second White Star ship to bear the name Britannic. She was the fleet mate of both the RMS Olympic and the RMS Titanic and was intended to enter service as a transatlantic passenger liner.
Britannic was launched just before the start of the First World War. She was designed to be the safest of the three ships with design changes actioned during construction due to lessons learned from the sinking of the Titanic. She was laid up at her builders, Harland and Wolff, in Belfast for many months before being put to use as a hospital ship in 1915. In 1915 and 1916 she served between the United Kingdom and the Dardanelles. On the morning of 21 November 1916 she was shaken by an explosion caused by a naval mine of the Imperial German Navy near the Greek island of Kea and sank 55 minutes later, killing 30 people.