The Han River extends for many miles east and west of Seoul. This section covers the primary Seoul Metropolitan area, from the western to eastern link-ups with the Seoul City Trail: Section 2, Achasan and Seoul City Trail: Section 7, Aengbongsan respectively.
Its a flat paved trail with specific lanes for bikes and walkers. Lots of parks along the way and other attractions. I strongly recommend going at night, the city-scapes are great.