The Hindenburgdamm is an 11 km-long causeway joining the North Frisian island of Sylt to mainland Schleswig-Holstein, off the coast of Germany. It was opened in 1927 exclusively for rail transport.
Before the causeway was built, the connection to the island was at the mercy of the tides, and in winter, the ice in the Wadden Sea formed an impenetrable barrier. The crossing took about six hours in adverse weather and flow conditions lasted longer. As the seaside resort of Westerland, on Sylt, became increasingly popular, officials started planning for the rail causeway.