Last summer, after six months of construction on a barge off the craggy Southern coast of Norway, developers and engineers filled the restaurant Under with 450 tons of water and were thrilled to watch it sink. When the structure’s 1600 tons of concrete had been manipulated into place by a floating crane and bolted to the ocean floor, and after the seawater had been pumped out and the unit sealed so none could rush back in, the owners had officially reached their goal. “It’s Europe’s first underwater restaurant,” says Stig Ubostad, who with his older brother and business partner Gaute Ubostad spent just over 8 million dollars to achieve their subaquatic dream. Under was not conceived by a well-known chef or restaurateur looking to add a remote and romantic new dining room as an exclamation point on an established culinary empire. The Ubostad brothers are fourth-generation hoteliers whose great-grandmother started the family business by opening a campground in the Norwegian municipality of Lyngdal in 1934. Gaute and Stig, 45 and 43, respectively, now run two comfortable, conference-hosting hotels in the area and were thinking about ways to boost tourism around Norway’s sparsely po...