The term "class" in the cruise industry refers to two very different things: ship design and service level. Primarily, cruise lines group sister ships into "classes" based on their blueprint; for example, Royal Caribbean’s Icon Class refers to its newest mega-ships, while the Vision Class refers to its smaller, more intimate vessels. However, many modern lines have introduced a "class-within-a-class" concept for passengers. This is a premium, gated area of the ship—such as The Haven by Norwegian, MSC Yacht Club, or Celebrity’s The Retreat—where guests pay a significantly higher fare for exclusive access to a private pool, a dedicated restaurant, 24-hour butler service, and priority boarding. While a standard cruise is "one class" for most, these luxury enclaves effectively create a multi-tier experience similar to international airline cabins, allowing travelers to enjoy the massive amenities of a giant ship while retreating to a quiet, high-end "boutique hotel" environment at night.