What's really interesting though, is that according to Google Earth this secret Chinese base is a tropical paradise. Not even 400 metres from one of these giant mountain-side entrances is what looks like a hotel... And then 600m from there is a very pleasant beach hut.
In fact, the whole area appears to be FULL of hotels and holidaymakers. There's dozens of images in the area, featuring scenic landscapes, tropical-looking beaches...
All right next to a naval base.