The "Quantum"-class of ships debuted as the second largest class of cruise ships in the world. The "Quantum"-class ships were the first ships built for Royal Caribbean by Meyer Werft since the "Radiance" class and share many features with those ships, including indoor pools with retractable roofs, vast expanses of glass, outdoor seating in the "Windjammer" buffet, and self-leveling pool tables. Other distinctive features of the "Quantum"-class include the "North Star" observation capsule mounted on the end of a crane arm, "RipCord by iFLY" a skydiving simulator, the three-deck-high Two70° lounge and performance venue at the aft of the ship featuring panoramic windows that convert into projection screens, and the multi-purpose SeaPlex facility which hosts activities such as basketball, roller skating, bumper cars, and a trapeze school. The "Quantum" class was the first class designed specifically for Dynamic Dining, and feature several separate complementary dining facilities instead of a single main dining room. Each venue will maintain the same menu and staff throughout the cruise. Unlike the earlier "Voyager", "Freedom", and "Oasis" class, "Quantum"-class ships do not feature a Viking Crown Lounge or ice skating rink, and the Royal Promenade mall down the center of the ship is not featured in its traditional form.