Intended for service in Asia, Ocean and her sister ships were smaller and faster than the preceding Majestic-class battleships, but retained the same battery of four 12-inch (305 mm) guns.

On 18 March, she attempted to retrieve the battleship Irresistible after the latter had been badly damaged by a mine in Erenköy Bay, but had to abandon her salvage efforts due to heavy Ottoman gunfire.

As was customary for battleships of the period, she was also equipped with four 18-inch (457 mm) torpedo tubes submerged in the hull, two on each broadside near the forward and aft barbette.

[4] Completed in early 1900,[5] Ocean was commissioned at Devonport on 20 February 1900 by Captain Assheton Curzon-Howe for service with the Mediterranean Fleet.

The following year she was reported to visit Port Lazaref (on the Korean peninsula) in October 1902,[9] but she suffered damage in a typhoon, and then underwent a refit that lasted into 1903.

On 2 June 1908, Ocean recommissioned for duty in the Mediterranean Fleet, undergoing a refit at Malta in 1908–1909,[3] during which she received fire control equipment.

In September 1914, she was ordered to relieve her sister ship Albion on the Cape Verde-Canary Islands Station, but while en route was diverted, first to Madiera and then to the Azores.

A landing party of 600 men, some of whom came from Ocean's detachment of Royal Marines, stormed the fortress and captured it, having encountered no resistance.

On 3–4 February, she and the armed merchant cruiser Himalaya supported ground troops against an Ottoman attack on the canal in the vicinity of El Kubri.

[3] On 28 February, she took part in an attempt to suppress the Ottoman defences in the Dardanelles led by Admiral John de Robeck; the battleships Albion and Triumph led the operation, and were tasked with neutralizing the repaired fortress at Dardanus, while Ocean and Majestic supported them by engaging batteries of mobile field guns that had proved to be troublesome in previous attempts to neutralise the Ottoman defences.

Ocean initially attempted to locate guns that had been active in the vicinity of Sedd el Bahr, before moving on with Majestic and coming under fire from several Ottoman batteries, including howitzers around Erenköy.

In the meantime, Albion and Triumph had approached Dardanus but they came under heavy fire from Ottoman guns on the European side of the straits, including the fortress at Erenköy, and were forced to circle to avoid taking hits.

Ocean and Majestic approached in an attempt to attack Dardanus, but they too came under renewed, furious fire from Erenköy, and de Robeck again ordered a withdrawal.

The northern group encountered similar resistance, but Ocean's gunners, more experienced from their operations of Basra the previous year, proved to be more effective than the other ships.

After a day's bombardment, the British sent in minesweepers to try to clear the minefields blocking the strait, and Ocean, Majestic, and several destroyers were tasked with protecting them.

Despite the heavy bombardment, the Ottoman defenses were largely intact, and even concerted firing from Ocean and other ships could not suppress the guns or their search lights.

The plan called for the battleships to enter the narrows and suppress the fortresses while minesweepers cleared paths in the Ottoman minefields.

[18][19] While retiring with Irresistible's survivors aboard, Ocean herself was hit by an artillery shell fired by Seyit Çabuk, an Ottoman Army gunner, and struck a drifting mine at around 19:00.

When destroyer Jed entered the bay later that evening to sink Ocean and Irresistible with torpedoes so that they could not be captured by Ottoman forces, the two battleships were nowhere to be found.