Longtan Lake is located in Longtan Village, Jiaoxi Township, Yilan County, Taiwan. It was formerly known as "Dapi" and is commonly known as "Dapi Lake". It was one of the "Twelve Scenic Spots in Lanyang" in the past and is also the largest of the "Five Famous Lakes in Lanyang". largest lake. Longtan Lake is surrounded by mountains on three sides. There are several temples on the mountainside. It is about 6 kilometers away from Yilan City. It covers an area of about 16 hectares and a water depth of 4.5 feet.

In the 75th year of the Republic of China (1986), it was announced as the "Longtan Lake Special Scenic Area".

The total length is about 3 kilometers. There is a unique round-nose catfish ecological park here, with a fishway about 30 meters long, where you can watch its production in the upper reaches of Shuo River. The production period is around the Dragon Boat Festival, which is a wonder. There is also a fish passage about 3 meters high. The small grassy slope of 1 meter is used for sliding on the slide, which is called the Big Bowl Slide. Adults and children can enjoy their happy time.