Rising sea levels are no longer an apocalyptic science-fiction trope; they're a daily fact of life. In the South Pacific, five of the Solomon Islands have been swallowed by the sea in the last couple years. Flooding of the Jersey Shore is now at least ten times as common as it was in the 1950s. This year, Venice will complete a costly set of sea-gates it hopes will save the city from storm surges. But there's one place on earth where worried residents are facing the opposite situation: sea levels that are actually falling. It's a bigger problem than it sounds like.

Land can rise and fall just like oceans.

Mean global sea levels rose almost seven inches during the 20th century, due to melting ice sheets and thermal expansion (water expands as it gets warmer). Sea levels rise quickest in places where the land is also subsiding at the same time, like Venice and the San Francisco Bay Area. But on the Baltic coast of Sweden and Finland, sea levels are dropping—because the land is rising.

The Nordic countries are bouncing back.

Sweden and Finland have been on their way up for 10,000 years. During the last Ice Age, massive glaciers formed all over Scandinavia, and they were so heavy that their weight warped the surface of the earth, pushing it down into the viscous mantle. When the ice melted, "post-glacial rebound" began, and Scandinavia is still rising at a rate of about 9 millimeters a year, three times faster than the Baltic Sea is rising.

Finland is on full tilt.

On paper, that might sound great. Finally, one place in the world where it's safe to build on beachfront property! And it's true that the Finnish coastline is visibly growing compared to photos from a century ago. But falling sea levels, just like rising ones, have their down sides. Not all of Scandinavia is rising at the same rate. In Finland, the west coast on the Gulf of Bothnia is rising faster than inland areas, so the nation is actually "tilting" upward to a small degree. That slight tilt is enough to affect river flow, leading to more frequent lowland flooding when snow melts every spring.

A shallow port is thinking deep thoughts.

There are other down sides as well. When coastlines grow, neighbors sometimes wind up in legal squabbles over who owns the new land. Lakes are now draining too quickly in some areas for summer swim parties. In port towns like Luleå, the rising land has made the harbor so shallow that it's endangered their shipping industry. Luleå plans to spend $200 million dredging the harbor over the next five years just to keep up with the uplift. Of course, the problem may be temporary. If global sea level rise accelerates, even the Nordic land elevator will no longer be able to keep pace.