Grottoes are natural or man-made caves, usually with attractive features such as waterfalls, lakes, or mineral deposits. Synonyms for the word grottoes include caverns, caves, underground chambers, subterranean recesses, and crevices. These structures can be found in many different parts of the world, often in areas that are prone to geological formations such as limestone or sandstone. Other synonyms for grottoes include catacombs, crypts, cellars, and tombs, which all refer to enclosed spaces underground. Whether natural or man-made, grottoes provide an opportunity for exploration and discovery, and are often a popular tourist destination.