Rimini - Caves Grotte di Onferno The Onferno caves have a karst structure whose exploration belongs to 1916 and that belong to the Oriented Nature Reserve of Onferno. We proceed with a qualified guide, follow a path that leads to an underground canyon, continue at a main channel that leads to the various rooms and narrows, characterized by various conical bumps inhabited by at least 6 species of bats. For more information you can visit the website of the municipality of Rimini.