South of the Ahr is the High Eifel (Hohe Eifel), with the Hohe Acht (747 m) being the highest mountain of the Eifel.
In the west, on the Belgian border, the hills are known as Schneifel (part of the Schnee-Eifel or "Snowy Eifel"), rising up to 698 m. Also in the west, by the Belgian and Luxembourg border, the region is known as Islek (Aquilania).
The southern half of the Eifel is lower. It is cut by several rivers running north-south towards the Moselle. The largest of these is the Kyll, and the hills on either side of this river are called the Kyllwald.
In the south the Eifel is concluded by the Voreifel above the Moselle.
In the Tertiary and Quaternary geological eras, the Eifel was a site of extensive volcanic activity. Some of the hills are volcanic vents. The peculiar circle-shaped lakes (maars) of the volcanic regions formed in volcanic craters. The last volcanic eruptions in the Laacher See volcanic site took place around 10,000 years ago and generated a huge volume of volcanic ash, now found in thin ash layers in contemporaneous sediments throughout Europe. The volcanism of the Eifel is thought to be partly caused by the Eifel hotspot, a place where hot material from deep in the mantle rises to the surface, and partly by melt-ascent at deep fractures in the Earth's crust. Research has shown that the volcanism is still active; the Eifel region is rising by 1–2 mm per year.
Historically, the Eifel volcanoes had inactive phases of 10,000 to 20,000 years between active phases, suggesting there is a possibility of future eruptions.
The Nürburgring, one of the world's most famous motor racing courses, is located in the Eifel. The northern loop (Nordschleife) of the course is also known as the Green Hell (Grüne Hölle), because of its long, difficult and dangerous path through the local forest.