The longest cruises departing from Southampton in 2026 are the World Cruises or "Grand Voyages," typically operated by lines like Cunard (Queen Mary 2 or Queen Anne) and P&O Cruises (Arcadia). These epic journeys can last anywhere from 99 to 120 nights. For example, a classic Cunard World Voyage might depart Southampton in early January and circumnavigate the globe, visiting over 30 ports across five continents before returning to the UK in late April or early May. These voyages are the "gold standard" of maritime travel, offering segments that cross the Atlantic, transit the Panama Canal, visit the South Pacific islands, and explore the bustling hubs of Asia and the Middle East. For those who don't have four months to spare, "Grand Voyages" of 28 to 45 days to the Caribbean or the Mediterranean are also popular "long-haul" options. These cruises serve as floating luxury resorts, providing a seamless way to see the world without the stress of flying, making them a top choice for retirees and "slow travel" enthusiasts in 2026.