Mount Dersa, or Jebel Dersa, is the ridge that rises behind Tétouan and gives the city its mountain backdrop. From the lower slopes you get a fine view over the white medina, the Spanish-era Ensanche, and the road out toward Martil and the Mediterranean.
This is a walk rather than a formal attraction, so go with sensible expectations: rough tracks, sun, and few facilities once you leave the edge of town. For independent travellers, it is one of the simplest ways to understand Tétouan's geography and to see how tightly the city sits between Rif foothills and sea.