Starting in the cosmopolitan city of Shanghai, 800 cruise guests are about to receive a crash course on sexuality in China. "It's a milestone in Chinese history", says Duan, one of the organisers of a trip set to culminate with a mass gay wedding, legal in international waters. He and his partner Li once made up one of China's 20 million fake marriages, having married women to appease their parents. "It was like being in jail. That kind of life was really torture for me", says Duan. But through a cruise dubbed "immoral" by Chinese authorities, they aim to confront the widespread belief that homosexuality is a disease that can be cured with treatments such as electro-shock therapy. Some remain unconvinced. "Chinese tradition is to pass on our genes to the next generation", says one father struggling to come to terms with the fact that his daughter is now living as a man. In China same sex couples are often treated as second class citizens, who can't get insurance, pensions or own a home.