Which of these shipwrecks did Jacques Cousteau discover?

HMHS Britannic was the third and final vessel of the White Star Line's Olympic class of steamships and the second 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 near the Greek island of Kea and foundered 55 minutes later, killing 30 people.

The wreck of HMHS Britannic is at 37°42′05″N 24°17′02″E in about 400 feet (122 m) of water. It was discovered on 3 December 1975 by Jacques Cousteau, who explored it. In filming the expedition, Cousteau also held conference on camera with several surviving personnel from the ship including Sheila MacBeth Mitchell, a survivor of the sinking. In 1976, Cousteau entered the wreck with his divers for the first time. He expressed the opinion that the ship had been sunk by a single torpedo, basing this opinion on the damage to her plates.