HMHS Britannic (/brɪˈtænɪk/) was the third and final 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 youngest sister of the RMS Olympic and the RMS Titanic and was intended to enter service as a transatlantic passenger liner. She was operated as a hospital ship from 1915 until her sinking near the Greek island of Kea, in the Aegean Sea, in November 1916. At the time she was the largest hospital ship in the world.