The Nanhu Island (南湖岛South Lake Island) is the largest one among the three islands of the Kunming Lake. This over one hectare (2.5 acres) island is located in the southeast of the lake, connected to the east bank by the Seventeen-Arch Bridge. Originally, the island and the whole Kunming Lake were artificial for thousands of workers designed it, excavating the lake thus making the island emerging from the earth and water. The whole island is edged by huge stones and enclosed with carved stone fences. Seen from the distance, the island together with the Seventeen-Arch Bridge look like a tortoise stretching its neck. Symbol of longevity in Chinese culture, the tortoise was a beloved animal for Emperors and especially Emperor Qianlong, who originally built this garden in the name of his mother's 60^th birthday.

On the island, two main buildings make the highlights of the site: the Hanxu Hall and the Dragon King Temple. The Hanxu Hall is the shelter where Empress Dowager Cixi inspected the navy drill. Every time she came to the Summer Palace, she made a stop-over for worshiping at the temple, using a boat to reach the holy island.