The cave
The Grotta di Onferno, known since the 19th century, is by far the best known cavity in eastern Romagna. It is a hydrogeological tunnel that develops in an allochthonous block of macrocrystalline plaster.
Two small streams descend from the clayey slopes of Monte Croce which, upon reaching the chalky cliff of Onferno, converge and begin to flow for a short stretch underground. The waters resurface a little further downstream, inside a densely wooded ravine. The cave of Onferno extends along the entire hypogean section of the watercourse. First explored in 1916 by Lodovico Quarina, who described its morphologies and concretions, the cave is now largely practicable and a destination for guided tours.
In the first section, along the stream, you go through tunnels set along fractures with vertical walls shaped by the water in sinuous forms. Subsequently the typical calcareous concretions (alabastrini) of the chalky caves are met; the larger ones, of a bright orange color due to the presence of iron oxides, form a beautiful flow which decorates a wall with active concretising dripping. In the following section, the active level is abandoned reaching fossil environments where some rooms have expanded due to the phenomena of collapse. In the Quarina Room the vault is animated by mamelons, curious conical structures that indicate the base of a layer of plaster. The climate here is warmer and drier than the tunnels where the water flows. Continuing, along some surfaces you can notice the bright inflorescences of chalky crystals grown on the selenitic rock.
The site is entirely included in the perimeter of the Onferno Nature Reserve and in SIC IT4090001 Onferno. Once the name of the place was Inferno (from the Latin infernum: low and dark place, due to the presence of caves) and only in the early nineteenth century was it changed to Onferno by the bishop of Rimini, who did not want such a name in his diocese. Among the main activities were the extraction and firing of chalk, which lasted until the 1950s. On the top of the cliff, where the castle once stood, remains a small village in a beautiful panoramic position on the reserve and the surrounding territories: towards the north you can recognize the unmistakable profile of San Marino, further east the sea. The visitor center, located in the ancient parish church of Santa Colomba, is the reference point for guided visits to the cave and excursions along the itineraries.

http://ambiente.regione.emilia-romagna.it/parchi-natura2000/aree-protette/riserve-naturali/onfe/geomorfologia
Tourist visit information
Type of active visit: tourist, speleological and didactic.

Tourist visit: 1.2km (300 m in the cave and 300 m of approach), duration 90 ''. Visit active all year round (P1: June-July / P2: August / P3: April-May and September-October / P4: November-March)

Speleological visits:
P1: 4 days / week, visits at 15.00 and 16.30 (Monday and Friday); (Sat and Sun) also 10.30am and 11.30am).
P2: visits at 15.00 and 16.30 (from Monday to Friday); (Sat and Sun) also 10.30am and 11.30am).
P3: Saturday, 3.00 pm and 4.30 pm; Sunday 10.30am, 11.30am, 3.00pm and 4.30pm.
P4: visits every Sunday at 11.30, 15.00 and 16.30. Holidays: visits both in the morning and in the afternoon
All year special openings for groups of min. 15 people.

Useful information: Cost: € 10.00 full; 8.00 reduced (3-12 years, over 65 and organized groups of 20 people). Clothing: Recommended comfortable clothing, trekking shoes or boots with a tessellated sole, a light waterproof jacket. Helmet with lighting is provided.

For information: onferno@nottola.org; tel. 389 199 1683

Website: www.facebook.com/grotta.Onferno
E-mail: speleo.la@nottola.org - onferno@nottola.org