caves are underground passages that go deep inside the earth. caves are created through a combination of chemical, water and pressure. the majority of caves are found in limestone areas. limestone is a very soft rock, so water can easily shape or carve out a cave.when it rain, water enters the soil and mixes with it. When the water comes through the soil, the oxygen (or carbon dioxide) creates an acid called carbonic acid, helping to dissolve the limestone. but sometimes,water only drips a little bit, this geologic process gradually eats away at the limestone and creates an underground hole. over time, the hole becomes larger and larger. over many thousands of years, the cave gradually gets bigger. Eventually it becomes bid enough to walk inside and explore.