Where is the dam of Dhul-Qarnayn located, and is it still existing and known today?

The Wall of Dhul-Qarnayn exists and will not perish until Allah's promise of the emergence of Gog and Magog comes to pass. The Prophet, peace and blessings be upon him, informed us that an opening the size of a ring had been made in it. Its exact location is not definitively known; it has been said to be behind China, or in Georgia in the Caucasus Mountains, or in the far north of the Earth. It is also possible that it is submerged under vast waters.