Kraft durch Freude (KdF; German for 'Strength Through Joy') was a German state-operated leisure organization in Nazi Germany. By 1939, it had become the world's largest tourism operator.

KdF was composed of several departments that had its own specific goals, with each department organizing different leisure activities. It organized activities such as sporting events on factory floors, art exhibitions, discounted concerts and, most famously and popularly, subsidized holidays and cruise trips.

KdF was supposed to bridge the class divide by making middle-class leisure activities available to the masses.

 It also sought to bolster the German tourist industry.

Most famously, the office also offered discounted cruise trips to German citizens. Although not initially planned to be a program offered by KdF, the initial successes of the cruises led to six large ships, including the MV Wilhelm Gustloff and the Mv Goya, being built specifically for use by KdF while a further six were chartered. They were first ships to be built specifically for cruises. They were collectively known as the KdF fleet, with the Robert Ley being considered as its flagship.