Why is Chengde a summer resort? Isn't it cooler near Qinhuangdao?

This has nothing to do with temperature. . . Chengde mountain resort was a royal garden built during the reign of Kangxi. It is the largest royal garden in northern China. The so-called summer resort is because the emperor comes to Chengde for summer every summer. . . Besides, when the emperor led the Eight Banners to hunt in the Mulan paddock in Chengde, they passed through Chengde. If the emperor leads the Eight Banners soldiers to go fishing in Qinhuangdao, maybe Qinhuangdao also has a summer resort, hahaha. . .