Specifically, the crew members discovered the stowaways on their way to port of Tilbury, UK.
As a result, the master had the stowaways locked away in a cabin and provided them with food during the voyage. However, the four Nigerian men escaped the accommodation and threatened the crew.
Grande Tema's 27 crewmembers locked themselves on the bridge to ensure their own security and alerted the British authorities. They put the vessel into a holding pattern in the English Channel, just off Margate, while they were waiting for help.
On December 21, 25 Royal Navy Marines from the Special Boat Service's X Squadron abseiled onto the Grande Tema's deck from helicopters and arrested the stowaways. No one was injured as they regained control of the ship in a 25-minute operation.
Essex police was overseeing the operation. Now, the four Nigerian men are being held under the UK's Immigration Act.
The four stowaways, named by UK authorities as Samuel Jolumi, 26, Ishola Sunday, 27, Toheeb Popoola, 26, and Joberto McGee, 20, have been accused with affray, a UK offense consisting of using or threatening to use unlawful violence.
The charge is often deployed after bar fights and soccer-match brawls, and it carries a maximum penalty of three years in prison. In a court hearing on New Years' Eve, the men did not enter pleas in response.
Finally, the prosecutor has the opportunity to also bring crucial charges under the UK's Aviation and Maritime Security Act, consisting of stiffer penalties for offenses related to vessel safety. During the hearing, the prosecutor asked the court for a three week delay in order to allow for more preparations, asserting that the case may be 'undercharged' relative to the severity of the alleged crime.