North Frisia went to bed with a southwest wind and woke, those who woke, to it swung round hard out of the northwest, pushing the sea over the dikes at the soft marsh edges. Around 15,000 people drowned that night in 1634, with the sheep and the cattle and whole parishes. The island of Strand came apart into Nordstrand, Pellworm and the low halligen, and the coast has kept that shape since. The old map still names the villages in German and Danish, Rungholt and Odenbüll and the rest.
Several of the churches lost that night survive only as foundations in the mudflat, courses of brick and boulder uncovered at low tide. People have walked out to Rungholt and found the sills of houses and the wells still lined. Nothing above knee height, and the sea comes back over it twice a day.
Nordstrand stayed an island for three hundred years after that night; the causeway out from the mainland only came in the 1930s. Pellworm is still reached by boat.