The trilevel, 164-passenger AmaSerena launched in 2015 and cruises along Europe’s Danube, Main, and Rhine rivers, starting from Budapest and docking in historic cities like Vienna and Linz. There are plenty of chairs on the top deck for soaking in the sun and the view, plus the petite swim-up bar/pool helps you cool off after guided walking and biking excursions in Melk, Austria, or Vilshofen, Germany. The top-deck eatery is a Chef’s Table, with reservations (and fancier dress) recommended. Atmosphere in the main dining room is more casual, but tables go fast.