The self-proclaimed most luxurious ship in the world, the Seven Seas Explorer is the flagship for Regent Seven Seas Cruises. The 738-passenger ship has a 3,875-square-foot, $10,000-a-night suite as its centerpiece. Its cocoon-inspired spa on Deck 5 offers Regent-exclusive treatments devised by Canyon Ranch SpaClub. Most of the extensive modern art collection displayed on the ship was hand-picked by parent company CEO Frank Del Rio and his wife.