Sinkhole may exhibit a visible opening into a cave below. In the case of exceptionally large sinkholes, such as the Minyé sinkhole in Papua New Guinea or Cedar Sink at Mammoth Cave National Park in Kentucky, an underground stream or river may be visible across its bottom flowing from one side to the other. Sinkholes are common where the rock below the land surface is limestone or other carbonate rock, salt beds, or in other soluble rocks, such as gypsum, that can be dissolved naturally by circulating ground water. Sinkholes also occur in sandstone and quartzite terrains. As the rock dissolves,
Akhayat sinkhole site presently there is no touristic activity. But Silifke governor said that the site will be opened to tourism. Akhayat sinkhole Akhayat (also known as Aşağı Dünya Obruğu) is a sinkhole in Mersin Province, Turkey. The Akhayat Sinkhole is located in a rural area of the Silifke district, to the north of Atayurt town. Its visitors (if there are any) are often from Mersin, and to get to the sinkhole site they follow the Turkish state highway . As for tourism nowadays, it isn't a particularly popular sight, as there is hardly any touristic activity apart from people driving past