She entered service with the Mediterranean Fleet until January 1901, when she was transferred to the China Station. "Ocean" was recalled from China in 1905 for service with the Channel Fleet after a period spent in reserve. From 1908 to early 1910, she was again assigned to the Mediterranean Fleet. She was assigned to the Home Fleet in 1910 and saw little activity until the outbreak of the First World War in August 1914. At the start of the conflict, she was assigned to the 8th Battle Squadron and was stationed in Ireland to support a cruiser squadron, but in October she was transferred to the East Indies Station to protect troopship convoys from India.