The Britannic, sister ship to the Titanic, sinks in the Aegean Sea on November 21, 1916, killing 30 people. More than 1,000 others were rescued. In the wake of the Titanic disaster on April 14, 1912, the White Star Line made several modifications in the construction of its already-planned sister ship.

The Titanic had two sister ships, the RMS Olympic and the HMHS Britannic, and neither is afloat today. The RMS Olympic, the only one of the trio to have a full and successful career, was retired and scrapped in 1935 after nearly 25 years of service. However, many of its opulent interior fittings, including the famous wood-carved "Aft Grand Staircase" paneling and stained glass, were sold at auction and can still be seen today at the White Swan Hotel in Alnwick, England, and in various private collections. The second sister, the HMHS Britannic, serves as a "time capsule" at the bottom of the Aegean Sea. It sank in 1916 after hitting a German mine while serving as a hospital ship during WWI. The wreck lies only 400 feet (122 meters) deep off the coast of the Greek island of Kea. Because it is in much shallower and warmer water than the Titanic, the Britannic is in remarkably good condition and is a popular (though strictly regulated) site for technical divers and scientific expeditions. In 2026, it remains the largest intact passenger ship wreck on the ocean floor, serving as a silent memorial to the Olympic-class era.