This region between federal roads B 4 between Ilmenau and Stützerbach, following the rivers Ilm, Lengwitz, and Nahe, and B 247 between Luisenthal and Suhl contains the three highest summits as well as the fifth highest summit of the whole range. The only settlements wholly within this region are Gehlberg north of Rennsteig and Vesser south of it. Parts of Schmiedefeld and Goldlauter-Heidersbach (part of Suhl) also extend into this part of the Forest. The highest summits crowning the mountain ridge are of volcanic origin. The terrain dips rapidly down to heights below 800 m towards the north-east, while heights remain above this altitude south-west of Rennsteig for some distance in the horseshoe-shaped Adlersberg massif.