Party organiser Christoph Stüber only wanted to attract a few dozen friends to the beach.
But his invitation circulated online and moved into bigger and bigger social networking circles. According to last estimates, around 13,500 people plan to show up on Saturday, an “unfathomable number” says the 26-year-old.
Part of Sylt's famed beach has been cleared of Strandkörbe, a type of sheltered beach chair, to prevent damage and destruction by raving hordes of revelers.
“We are hoping for a smooth run and respectful conduct,” said Sylt Mayor Petra Reiber.
About 100 portable toilets have also been placed on the beach to give partiers an alternative to fouling the sand.
“We all want peaceful celebration. Sylt will not go under because of us,” Stüber said.
The police are already planning to be present at the nearest train station, with 100 riot police from the mainland helping to keep order.
The local railroad expects surge of revelers on Saturday between Hamburg and Sylt and plans to add extra cars to transport them there and back.