Aachtobel, Nature reserve in Frickingen, Germany.

Aachtobel is a nature reserve spanning three towns - Frickingen, Owingen, and Überlingen - with forests, streams, and steep hillsides creating varied habitats at different elevations. The terrain features wooded valleys and rocky slopes where plant life and wildlife adapt to local conditions.

The Aachtobel was designated a nature reserve by decree of the Badische Minister of Culture and Education on 24 March 1939, under reserve number 4.057, making it one of Germany's oldest protected areas. The designation is now administered by the Regierungspräsidium Tübingen. The reserve covers about 72 hectares: 52 in Owingen, roughly 15 in Überlingen and nearly six in Frickingen.

At the southern edge of the gorge stands the pilgrimage site Maria im Stein, whose chapel holds many votive tablets left by pilgrims. One tablet records that Alberto von Bodmann, after escaping Turkish captivity, built a church here at the spot where he first saw his ancestral castle again, fulfilling a vow to the Mother of God; he died in 1217.

The reserve is best explored on foot with pathways winding through valleys and woodlands. Wear sturdy footwear, as trails can be uneven and some sections have steep drops.

The Großes Zweiblatt orchid, chosen Orchid of the Year in 1992, grows here, and the Ulmen-Zipfelfalter butterfly depends on elm trees in the gorge. The Maria im Stein chapel at the southern rim holds votive tablets; one records Alberto von Bodmann, who founded a church after escaping Turkish captivity and died in 1217.