The entrance to a long tunnel is seen inside a warehouse near the Mexican border in Otay Mesa, California November 3, 2010. U.S. border police have found a sophisticated smuggler's tunnel the length of six football fields linking Southern California with Mexico and believed to have been used by drug traffickers, authorities said on Wednesday. Agents also recovered more than 20 tons of marijuana during overnight searches of the tunnel, the border patrol said in a news release. REUTERS/Nelvin C. Cepeda/San Diego Union-Tribune/Pool (UNITED STATES - Tags: POLITICS CRIME LAW SOCIETY)
A look at various smuggling tunnels across the U.S.-Mexico border.