A new report by the London-based Environmental Justice Foundation estimates 27 million people are victims of human trafficking around the world. Many are sold into sex slavery.
But in Thailand, men are being trafficked to work in the fishing industry. They are forced to labour for up to 20 hours a day with little or no pay.
The UN has found that nearly 60 percent have witnessed the murder of a fellow worker.
Al Jazeera's Wayne Hay reports from Thailand.