I am wondering if there still a cruise ship from Xiamen to Hong Kong?

Biron, I am afraid that there is no cruise ship from Xiamen to HK. You need take high speed train from Xiamen North to Shenzhen North. It takes around 4 hours and costs CNY150. Then you can change longhua subway line to get off at Huizhanzhongxin. There you can take Luobao line to reach Luohu. Finally you can go to HK by passing Luohu Border.