The Dornier DO X 1929-1932 was the largest, heaviest, and most luxurious seaplane ever built. It was built to carry 66 passengers on long-distance flights or 100 on short flights with luxurious accommodations up to the standards set by the top-end steamship liners. There were three decks, which featured a smoking room with bar, a dining salon, and seating for the 66 passengers which could also be converted to sleeping berths for night flights.

A series of unlucky, non-fatal accidents occurred during the planes’s first flights, the Depression ruined Dornier’s marketing plan, and manufacturing was suspended after only the first three examples had been built.