Bay of Aarhus, Denmark — Below the dark blue waters of the Bay of Aarhus in northern Denmark, archaeologists search for coastal settlements swallowed by rising sea levels more than 8,500 years ago. This summer, divers descended about 26 feet below the waves close to Aarhus, Denmark's second-biggest city, and collected evidence of a Stone Age settlement from the seabed. It's part of a $15.5 million six-year international project to map parts of the seabed in the Baltic and North Seas, funded by the European Union,...