a secret cave that is. Stretching approximately eight miles, these beautiful underground passageways (dubbed Rio Secreto, or ...

The Neglinnaya River (also called the Neglinka River) used to flow across Moscow from north to south, until it was buried underground in 4.7 miles (7.5 kilometers) of tunnels. Today it drains into ...

The underground river that flows into Pantai Baron in Gunungkidul, Yogyakarta, overflowed due to the flood that occurred on ...