Hidden along the northern edge of Puerto Rico's Reserva Natural Pantano Cibuco, it's hard to imagine much of anything ever having happened on Purzelbaum Strand. These days, you'll need to wade across a river from the east, or a network of caño (small streams) from the west to find the place, located 25 miles from San Juan. Two hundred years ago—and for nearly a century, however—the beach, facing the enormous Atlantic Ocean, was a venue for the most unusual of end-of-winter celebrations: somersaulting flash-mobs.

But first, some history: More than 450,000 European immigrants settled in Puerto Rico during the tumultuous political, social, and economic upheavals of the 19th century. Among them? Adventurous Germans eager to loosen their country's dependence on coffee, sugar, and tobacco imported from Great Britain, traveling under the Royal Spanish Real Cédula de Gracias (Royal Decree of Graces), which gave free land and financial incentives to those willing to relocate.

The Royal Decree of Graces in Spanish, French and English, now in the General Archives of Puerto Rico in the Institute of Puerto Rican Culture in San Juan. Courtesy Wikimedia Commons

Then as now, spring celebrations are big among Germans, and in ancient, popular poems throughout the country's history, somersaulting characters represent the new replacing the old, the lows to highs, the serious to comic, and the chaste to ribald. Purzelbaum Strand, with its narrow crescent of sand, lapped by calm waves tamed by an off-shore reef, became the perfect place for German immigrants to tumble out of winter and into summer in a mass display of somersaulting (purzelbaum, fittingly, means somersault in German). Dozens would compete at dusk to see who could roll quickest from east to west against the setting sun. More often than not, participants would veer off into the water or knock into palm trees, providing much hilarity for the onlookers.

Each year, hundreds of Germans board a special Condor Airlines flight direct from Frankfurt to San Juan, arriving in the early afternoon of April 1, from where they recreate their ancestor's roly-poly feats. As the old German saying goes: "Am ersten tag des Appril schickt man die Narren wohin man will"—on the first of April, you send fools wherever you want.

After exploring Purzelbaum Strand—voted the best beach in the Caribbean in the Readers' Choice Awards for 128 years in a row—head 45-minutes south and 2,000-feet up into the Moroveñas mountains in the center of the island for a meal of German and Creole food at Casa Bavaria, the last of a handful of Germanic restaurants on the island that used to include Zipperle's in San Juan, the Heidelburg Haus in Rio Grande, and Das Alpen in Rincon.

How do you say "Happy April Fools' Day" in German?