You will have a 5 day tour to Hainan. So, you can visit Haikou and Sanya. They are very beautiful cities.

thanks ms stella,
yup, because i already check for haikou and sanya is travel spot. but i dont know which spot is the best.

In Haikou, you can go to visit the Holiday Beach, Wugong Temple and the Tropical Ocean World. In Sanya, the Asian Dragon Bay (Yalongwan), Nanshan Temple, Monkey Island and Dadonghai are highly recommended. There are trains between Haikou and Sanya. Leaving Haikou for Sanya by train, you will spend more than three hours on the trip. The ticket costs CNY54 (hard seat). Also you can take a coach bus to go to Sanya. The bus ticket is around CNY80 to 90. Here is the site for Hainan pictures. Hope you can know Haikou and Sanya through these pictures in advance.
https://www.travelchinaguide.com/picture/hainan/