Federal agents in Calexico discovered a 140-foot-long tunnel across California's border with Mexico, officials said this week.
An agent on patrol two miles east of the Calexico Port of Entry noticed "a depression in the soil" along the All-American Canal that runs parallel to the border, the U.S. Customs and Border Patrol said in a statement Friday.
The patch of soil collapsed as the agent approached, exposing a hole 18 inches wide. Lumber and wiring were visible inside.
Investigators determined that the entire tunnel was about 3 feet wide and 142 feet long, or slightly shorter than an Olympic-sized swimming pool. The tunnel ended in Mexico, about 60 feet south of the border, in an area that is primarily open fields and farmland.
The Border Patrol did not specify what, if anything, had passed through the tunnel. But they noted that "anything or anyone could potentially cross into the U.S."
Last month, agents discovered a smuggling tunnel that ran nearly a quarter of a mile underneath the border, from the El Sarape restaurant in Mexicali, Baja California, into the living room of a home in Calexico. The exit to the tunnel was covered with tile, officials said.
U.S. Homeland Security agents used wiretaps to track the construction of that house, which was finished in December at a cost of about $86,000. The investigation led to the arrests of four people and the confiscation of more than a ton of marijuana.
Last April, officials observed a man in a wetsuit emerge from the All-American Canal. Investigators later found a 230-foot tunnel beneath the border that had lighting and ventilation, as well as 25 sealed packages of methamphetamines with a street value of about $700,000.