I’ll tell you what I know (may not be accurate as I’ve never been there) if you promise not to try and sneak in.
The place is called Ling Ding Dao (Ling Ding Island). It’s somewhere near Zhuhai. It was made famous by workers working on the Lantau airport. Most probably they jumped into the company boat every day after work to get their hair washed across the waters as it was so near. People from Hong Kong (mongerers) caught on and went there by speedboat (those used to smuggle goods and people) from Hong Kong and the place flourished. I haven’t heard anything about it in the past few years. It must have died down when the airport was completed and all the workers left Lantau.
I think you can still get there via ferry from Zhuhai. If you are really curious take the ferry and check out the place. Let us know if the old Ling Ding Dao still exists.