It is said that Yilan is shaped like a turtle and a snake guarding the river mouth. The turtle refers to the Turtle Island in the Pacific Ocean to the east, while the snake refers to the 106-kilometer winding coastline that stretches from Da'ao of Shicheng Village in the north to the mouth of the Heping River at Aohua Village of Nan'ao Town in the south. This smooth and slightly bending curve is roughly divided into three sections. The area from Da'ao of Shicheng Village in Toucheng to North Harbor at Wai'ao Village is a narrow rocky coastline formed by the mountains leaning directly over the sea. The coastline is full of twists and turns with many peninsulas, capes, and bays and harbors. The coastal area is narrower along a rocky coast. The land rises and falls to a greater degree and the sea runs deeper offshore. This area is a part of the Jiaoxi Fault Coast.
