No, Harmony of the Seas does not have a SeaPlex. The SeaPlex is a signature feature of Royal Caribbean’s Quantum Class and Quantum Ultra Class ships (like Anthem of the Seas or Odyssey of the Seas). Harmony of the Seas is an Oasis Class ship. Instead of the indoor SeaPlex sports arena, Harmony features the "Pool and Sports Zone" which includes the Ultimate Abyss (a 10-story dry slide), twin FlowRider surf simulators, a zip line, and a miniature golf course. While Oasis-class ships like Harmony are larger overall and offer "neighborhoods" like Central Park and the Boardwalk, they focus more on outdoor thrills and open-air spaces, whereas the Quantum-class SeaPlex provides an indoor, multipurpose space for bumper cars, roller skating, and basketball.