The Caoling (Tsaoling) Historical Trail connects Gongliao (貢寮) with Dali (大里) on Taiwan's northeast coast. It was originally constructed in 1807 and provided an important transport link between Taipei and Yilan (the only other alternative at the time was to travel by sea). Now it is just a destination for walkers and tourists. The Taiwan Lonely Planet Guide says, "If you can only do one hike during your stay in Taiwan, make it this one".
The trail is 8 kilometres long and depending on your level of fitness will take around three or four hours to hike one way. When you reach the pass you will be rewarded with spectacular views of Taiwan's northeast coast. The trail is easily accessible by train. Catch a train to Gongliao and then return to Taipei by catching a train from Dali. An alternative route is to follow the ridge from the pass along the Taoyuan Valley trail. You can then descend to Daxi (大溪) from where you can also catch a train.