Oceania's Regatta was built in 1998 but underwent a multimillion-dollar refurbishment in 2014, with upgrades including teak, custom stone and tile work, and plush cabin makeovers. With only 684 passengers, the midsize ship has the Old World feel of a traditional hotel. But despite formal touches like a grand stairway, life aboard this ship is relatively casual. There are no formal nights, and dining is all open seating.