The Sandiaoling Tunnel, located between Ruifang Station and Shuangxi Station in New Taipei City, is a popular spot for cyclists and nature enthusiasts. This eco-friendly tunnel is part of the Youth Mountain and Sea Line initiative and features Taiwan's first "steel bikeway." With a length of 3.19 km, the tunnel offers a unique biking experience with its stunning pond design and mirror-like reflection.

Visitors can also enjoy informative boards and tour guide services along the route. However, due to limited space, visitors are required to apply for entry before their visit. So, if you're looking for a fun and environmentally-friendly adventure, don't miss out on the Sandiaoling Tunnel!