Lalu Island (Thao language: Lalu; Chinese: 拉魯島; Pe̍h-ōe-jī: Lalu Tó; pinyin: Lālǔ Dǎo) is a small island in Sun Moon Lake, Yuchi Township, Nantou County, Taiwan. The island used to be much bigger, separating the lake into a part shaped like crescent moon and another part shaped like a round sun.
When the island was still bigger, people lived on it; in fact, the locals called it "Pearl Mountain"(Chinese: 珠仔山 or 珠嶼; Pe̍h-ōe-jī: Chu-á-sū / Chu-sū) ever since the Qing dynasty. Under Japanese rule, the island was renamed "Jade Island" (Japanese: 玉島), and in the 1930s, the Japanese built a dam that raised the water level in the lake and almost entirely flooded the island.