Every year around April to May, Tung flower festival is in Sanyi. Tung flowers are white flowers that present in where Hakka people live.
Hire a scooter or bicycle around San-Yi rail station, price is around NT$ 250~400 for one scooter. Do not expect to hike around San-Yi by walking.
Old Shang-Xin Rail station, most famous spot in San-Yi. It's a rail station which is not operation anymore, you can walk on the railway, or just have a lunch or tea around the station. Follow the road in front the Shang-Xin station, you will arrive Long-Teng Bridge. Longteng Bridge is an old railway bridge, which broke by earthquake several years ago.
Having some snack in Sanyi downtown; You must try "Ban-Teo", most representable Hakka food. Then ride the scooter to Tong-Lo, a neighbor town of Sanyi, and go along with the way to Jiu-Hua-Shan. You might enjoy the forest and tea farm around this mountain road.
Related websites:
Miaoli county travel information 苗栗縣觀光旅遊網
Taiwan: Touch your heart
San-Yi information 三義觀光資訊