The U.S. Customs and Border Protection agency said the tunnel linked warehouses in Otay Mesa, California, and Tijuana, Mexico. It measured 1,800 feet and was equipped with a rail system, lighting and ventilation.

U.S. Immigration and Customs Enforcement via AP
In this photo provided by U.S. Immigration and Customs Enforcement, a federal agent crawls through a 600 yard tunnel found in a warehouse along the border between the United States and Mexico on Wednesday, Nov. 3, 2010, in San Diego. U.S. authorities have discovered 20 tons of pot near the tunnel.