Click on the video to get an inside look of the highly sophisticated tunnel that stretches almost a mile from Tijuana to San Diego.

San Diego Border Patrol Agents are calling this a high-level narco-tunnel

They dug into a portion of the ground to gain access because the entrance was blocked.

It was finally exposed in August after a multi-year investigation, and just announced this week.

It includes an extensive rail-cart system, forced air ventilation, high voltage electrical cables and panels, an elevator at the tunnel entrance, and a complex drainage system.

The tunnel begins in an industrial area in Mexico that’s just about half a mile west of the Otay Mesa port of entry.

Mexican authorities discovered the entrance to the tunnel and the San Diego Tunnel Task Force began investigating.

It travels into the U.S. extending more than 4,000 feet from the border, but didn’t appear to be in use.