Which one is more fun, Yalong Bay, Dadonghai, Sanya Bay or Wuzhizhou Island?

The ones you mentioned are all the most famous attractions in Sanya, and they are also must-visit attractions. In terms of fun, they are almost the same. If time permits, it is recommended to visit them all. If time is limited, it is recommended not to miss Yuzhizhou Island and Yalong Bay, which are more representative.

It is recommended that you download a professional travel APP, Qingyi, which has detailed attraction guides for your reference.