If you are looking for a fun day trip from Taipei then this could be your spot! It is located in New Taipei City and is a historic railway tunnel that now allows visitors to ride bikes through it. It's a very relaxing activity that you can do and enjoy some fresh air.
A round bicycle tour through the tunnel is 15 to 20 minutes. On foot, it takes more than half an hour. Its is free to enter but for the bikes you need to rent them.
How to get there?
Take TRA to Fulong Station, then take TRA to Ruifang Station and transfer Gold Fulong Shuttle Bus 856 to Fulong Visitor Center stop, then take TRA to Keelung Station and transfer Keelung Bus 791 to Fulong stop.