At a glance there is nothing wrong with this beach - has white sand, seaweed, bathers, tiny waves, rocky cliffs, and is subject to tides, but it's NOT ON THE OCEAN. IT IS IN THE MIDDLE OF AN AGRICULTURAL FIELD.
Located near the town of Llanes in Asturias in northern Spain, the odd little beach of Gulpiyuri stands by itself in a depression in the middle of an agricultural field. Declared a Spanish Natural Heritage site, the beach and lagoon are actually a karst sinkhole, created when the nearby Cantabrian Sea dug through the limestone cliffs, making underground tunnels for the sea to come through, and collapsing the roof of a limestone cave. At high tide, the sinkhole fills with ocean water.