By Agence France-Presse
The men were given the maximum allowable sentence on a raft of charges, including rape, following their arrest more than two years ago for the attack on the Thai island Koh Kut, also known as Koh Kood.
“All five defendants were found guilty of rape, light assault and serious assault,” a court official in Thailand’s Trat province said, adding that they were also fined.
One was also convicted of attempted murder, said the official, who did not identify the defendants by name.
The secluded and underdeveloped island of Koh Kut is close to Thailand’s eastern border with Cambodia, and police say the men swam to the beach to attack the group of four French holidaygoers at knifepoint in February 2016.
Two injured men escaped to alert authorities and the fishermen were arrested shortly afterwards.
While Thailand remains a safe destination with 35 million visitors last year, a number of gruesome, headline-grabbing crimes against foreigners have hurt the country’s reputation as a tourist haven.
In 2015 two Myanmar migrant workers were sentenced to death for the 2014 murder of two British backpackers, one of whom was raped, on the diving island of Koh Tao after an investigation and trial that was widely criticised as unfair.