. >> reporter: above ground, this is a tiny tijuana villa. beneath it, a mammoth secret. drug tunnel, officials say, was over eight football fields long. >> we believe this so be the longest tunnel that we've discovered in this district to date. >> reporter: hacked out mostly by hand, but with lights, ventilation and this freight elevator capable of holding up to ten people. the tunnel stretching from tijuana to the border fence, and then another 500 yards to a nondescript lot near san diego. ending up as a three-foot wide hole covered by a giant dumpster. inside, 2,000 pounds of cocaine. the largest ever coke seizure from a tunnel into california. plus, 14,000 pounds of marijuana. we recently embedded with a border protection tunnel team. you do a 4,000-pound load of marijuana, you sell it, does that pay for the tunnel? >> i'm sure that pays for the tunnel easily. >> reporter: in order to dig that tunnel, 900 feet in that direction, they had to remove hundreds of tons of dirt, and yet the neighbors say they saw nothing and heard nothing. officials say there are likely ma

. >> reporter: above ground, this is a tidy tijuana villa. beneath it, a mammoth secret. a drug tunnel, officials say, was over eight football fields long. >> we believe this so be the longest tunnel that we've discovered in this district to date. >> reporter: hacked out mostly by hand, but with lights, ventilation and this freight elevator capable of holding up to ten people. the tunnel stretching from tijuana to the border fence, and then another 500 yards to a nondescript lot near san diego. ending up as a three-foot wide hole covered by a giant dumpster. inside, 2,000 pounds of cocaine. the largest ever coke seizure from a tunnel into california. plus, 14,000 pounds of marijuana. we recently imbedded with a border protection tunnel team. you do a 4,000-pound load of marijuana, you sell it, does that pay for the tunnel? >> i'm sure that pays for the tunnel easily. >> reporter: andn order to dig that tunnel, 900 feet in that direction, they had to remove hundreds of tons of dirt. and yet the neighbors say they saw nothing and heard nothing. officials say there are likel

. >> reporter: that engineering marvel started at this tijuana villa.a kiddie pool and birdbath. below ground a half-mile-long secret snaking to a san diego suburb. >> we believe this to be the longest to date. tunnel that we have discovered in this district. >> reporter: dug mostly with hand tools equipped with light, ventilation and this motorized freight elevator capable of carrying up to ten people. this gopro video from border agents shows the tunnel from the inside barely three feet wide but nearly nine football fields long. the end of it this tiny hole hidden by a dumpster. authorities arresting six people seizing more than $22 million worth of cocaine alone and 14,000 pounds of marijuana. we believe this to be the largest single seizure of cocaine related to a tunnel along the california/mexico border. over the years they have discovered 180 drug smuggling tunnels. along the u.s./mexico border. >> we recently squeeze into one of those tunnels with the u.s. border protection tunnel team. that right there is the border fence which means that that