The Portuguese luxury cruise ship Santa Maria is hijacked by opponents of the Estado Novo regime with the intention of waging war until dictator António de Oliveira Salazar is overthrown.

The Santa Maria hijacking was carried out on 22 January 1961 when Portuguese and Spanish political rebels seized control of a Portuguese passenger ship, aiming to force political change in Portugal. The action was also known as Operation Dulcinea, the code name given by its chief architect and leader, Portuguese military officer, writer and politician Henrique Galvo, who had been exiled in Caracas, Venezuela since 1959. After United States naval intervention, the ship arrived in Brazil, and the hijacking ended on 2 February when the rebels were given political asylum there.

Cruise ships are large passenger ships used mainly for vacationing. Unlike ocean liners, which are used for transport, cruise ships typically embark on round-trip voyages to various ports-of-call, where passengers may go on tours known as "shore excursions". On "cruises to nowhere" or "nowhere voyages", cruise ships make two- to three-night round trips without visiting any ports of call.

Modern cruise ships tend to have less hull strength, speed, and agility compared to ocean liners. However, they have added amenities to cater to water tourists, with recent vessels being described as "balcony-laden floating condominiums".

As of December 2018, there were 314 cruise ships operating worldwide, with a combined capacity of 537,000 passengers. Cruising has become a major part of the tourism industry, with an estimated market of $29.4 billion per year, and over 19 million passengers carried worldwide annually as of 2011. The industry's rapid growth saw nine or more newly built ships catering to a North American clientele added every year since 2001, as well as others servicing European clientele until the COVID-19 pandemic in 2020 saw the entire industry all but shutdown.As of 2022, the world's largest passenger ship is Royal Caribbean's Wonder of the Seas.