In May, one of the largest ships ever to cruise on a European waterway launched on the Danube, central Europe’s longest river, which runs through lush countryside and capital cities including Budapest and Vienna. The AmaMagna, built exclusively for the Danube’s wide expanse, provides cruisers with ample personal space—from cabins that look more like five-star hotel rooms to a pool on the roof. All excursions on shore are included in the offerings, which start at $3,799 for a seven-day cruise. —Billy Perrigo