This photo is thought to be of survivors of the sinking of the HMS Triumph on 25 May 1915.
HMS Triumph, originally known as Libertad, participated early in the war in the hunt for von Spee's German East Asia Squadron and in the campaign against the German colony at Tsingtao, China. The ship was transferred to the Mediterranean in early 1915 to participate in the Dardanelles Campaign. HMS Triumph took part in the opening attack on the entrance forts on 18 February and 19 February, and joined the predreadnoughts Albion and Cornwallis in using her secondary battery to silence the fort at Sedd el Bahr on 25 February. She was one of the first Allied battleships to enter the Turkish Straits during the campaign when they carried out the initial attack on the inner forts on 26 February. She also took part in the attack on Fort Dardanos on 2 March 1915. She was torpedoed and sunk off Gaba Tepe by the German submarine U-21 on 25 May 1915. Three officers and 75 enlisted men died in her sinking.