26 May 2023 Measuring 293.3m in length and weighing 99,536 in gross tonnage TUI cruise ship Mein Schiff 3 takes the accolade of the largest ship to ever sail into Portsmouth harbour, demonstrating the growing capabilities of Portsmouth International Port to manage a wider range of ships.

As of 2026, the "biggest" ship in the TUI fleet depends on which TUI brand you are referencing. For Marella Cruises (TUI's UK-based brand), the biggest ship is the Marella Voyager, which debuted in 2023 and has a gross tonnage of approximately 77,000 tons, accommodating around 1,900 passengers. However, if you are looking at TUI Cruises (the German-based joint venture with Royal Caribbean), the biggest ship is the Mein Schiff Relax, the first of the "InTUItion" class, which launched in 2025. This massive vessel is significantly larger, at roughly 160,000 gross tons, and can carry nearly 4,000 passengers. In the world of river cruising, the newest and largest ship in the TUI River Cruises fleet is the TUI Aria, which debuts in the summer of 2026. While "large" for a riverboat at 190 passengers, it is tiny compared to the ocean-going giants. For most travelers looking for the ultimate "mega-ship" experience with TUI in 2026, the Mein Schiff Relax is the flagship of the fleet, featuring a futuristic design, an expansive spa, and a much larger variety of dining and entertainment options than the older, smaller vessels.