San Diego Tunnel Task Force, in collaboration with their enforcement counterparts in Mexico, have uncovered two sophisticated smuggling tunnels connecting commercial buildings in San Diego's Otay Mesa industrial park with warehouses in neighboring Tijuana, Mex., April 2, 2014.
This Oct. 30, 2013, photo released by U.S. Immigration and Customs Enforcement shows a tunnel linking warehouses in Tijuana, Mexico, and San Diego to smuggle drugs. The tunnel is equipped with electricity, ventilation and a rail system, making it one of the more sophisticated secret passages discovered along the U.S.-Mexico border.
San Diego Tunnel Task Force agents and local authorities seized more than 8 tons of marijuana and 325 pounds of cocaine from the tunnel between Tijuana and San Diego, marking the first time cocaine has been recovered in connection with a local drug tunnel. In this photo, Homeland Security special agents examine the seized drugs.
The entrance to a cross border illegal tunnel is lit by a lamp after it was found underneath a bathroom sink by the Mexican army inside a warehouse in Tijuana, Mexico, in July 2012. The 220-yard tunnel, presumably designed to smuggle drugs into the United States, was incomplete and had not yet crossed beneath the border.
A Homeland Security special agent, who chose to remain unidentified, crawls through a drug tunnel found by agents at a warehouse near the U.S.-Mexico border in November 2010. Authorities confiscated over 30 tons of marijuana in the tunnel, which connected to a warehouse in Tijuana, Mexico, in one of the largest pot seizures in U.S. history.
View of a trans-border tunnel and wagons found near the Tijuana airport in November 2011. Mexican authorities said the 1,800-foot drug smuggling tunnel beneath the US border was the second found in the area in a month.
Mexican Army soldiers stand at the entrance of a clandestine tunnel connecting warehouses on either side of California's border with Mexico in Tijuana in November 2010.
An open bundle of marijuana seized in a warehouse along the U.S.-Mexico border in November 2010 near San Diego. U.S. authorities discovered 20 tons of pot near the tunnel.
Frank Marwood, with U.S. Immigration and Customs Enforcement officer, leads a tour through a drug tunnel along the Mexico-U.S. border in January 2006. Authorities said the 2,400-foot tunnel ran from Tijuanan to a warehouse in Otay Mesa, Calif. The tunnel was furnished with lighting, ventilation and equipment to pump out ground water.
View of electrical wiring in a drug tunnel found along the Mexico-U.S. border at a warehouse in Otay Mesa, Calif.
Not all drug tunnels connect the U.S. and Mexico. U.S. and Canadian law enforcement officers arrested three men and discovered a drug smuggling tunnel leading between two houses on either side of the border in Washington state and the Canadian province of British Columbia in July 2005. The property at the Canadian end of the tunnel, seen here, is in Aldergrove, B.C.
This handout from the Drug Enforcement Administration shows the cross border tunnel between Lynden, Wash., and Aldergrove, B.C., Canada in July 2005. Three men living in Surrey, B.C., were charged with conspiracy to distribute marijuana and conspiracy to import marijuana.
Mexican Federal Police officers check the interior of a chimney that served as an entrtance to a tunnel discovered February 2002 that was used to transport drugs between Mexico and California. The tunnel, approximately 1,000 feet long and 4 feet in diameter, connected a private home in the mountains east of San Diego to a house in the Mexican border town of Tecate. It may have also been used to smuggle illegal immigrants, authorities said.