In the north west of Sardinia, close to Porto Conte bay, Alghero territory, there are more than 300 caves above and below water, with about 30 large, and many smaller, underwater sea caves in the limestone cliffs of Capo Caccia and Punta Giglio. The Nereo Cave is the most important and is considered the largest in the Mediterranean Sea. On the east side of Sardinia there are many underwater cave systems starting from the Gennargentu Mountains, with underwater rivers. There is a fresh water cave of more than depth in this area.