Yilan is located in the north-east of Taiwan. It is known as a historical center for some of the many native peoples. Geographically, Yilan is characterized by mountains, rocky sea, and torrential rains. The city of Yilan is located on the second-largest level of Taiwan – the Yilan Plain.
The majority of the approximately 460,000 inhabitants live in the mouth of the river Lanyang along the Pacific coast in the north-east of the county. About 10 km off the coast lies the volcanic island Guishan Dao (turtle island), which is today uninhabited and designated as a nature reserve.
The county of Yilan is a popular excursion destination, especially for residents of nearby Taipei. The most important tourist center is the town Jiaoxi, known for its hot springs, in the north. There are some hiking trails in the mountains, especially in the tourist areas of Taipingshan, Qilan, and Mingchi in Datong County, west of the county.