Regal Princess underwent a special dry dock at Damen Shiprepair Rotterdam from late April into early May 2025. The ship arrived at the Rotterdam facility on April 25 and resumed passenger service on May 9. Princess arranged the unscheduled project to address an essential technical issue that had affected the ship's winter operations but was not described as compromising its safety certification or passenger facilities.

The central task was replacement of a failed diesel-generator engine. Damen's project team prepared the vessel before docking, then removed exterior shell plating and an internal bulkhead, cleared piping, pumps and walkways, installed skidding tracks and lifted the failed engine out. The replacement engine was installed by reversing that process, after which the affected structure and systems were restored. The project also included hull painting, technical servicing and general upkeep. The April 4 transatlantic voyage was shortened, and a subsequent cruise was canceled to create the repair window.