Shenzhen is the place where a lot of the world's technology is manufactured -- smartphones are made by Foxconn and other companies, drones are designed and built by DJI, and so on. The technology hub is located just north of Hong Kong, which is a special administrative region of China and is treated somewhat like a separate country...although it's not. Recently, drones were used in a smuggling ring in which almost $80 million of refurbished iPhones were transported from Hong Kong to Shenzhen, in what appears to be a "coals to Newcastle" operation.
The refurbed iPhones can be sold for quite a bit on the Chinese black market, so it's a lucrative business. The 26 suspects arrested in the operation used drones to fly a pair of 200-meter (660 foot) cables between Hong Kong and the mainland to transport the refurbished phones.
The smugglers would usually start up after midnight, and needed very little time to get the cables in place. Small bags holding 10 or more iPhones were then transported across the cables into Shenzhen. The team could smuggle up to 15,000 phones across the border each night.
China is seeing increasing issues with drones, and published strict rules last year to keep drones from flying into aircraft flight paths and requiring drone owners to register their aircraft under their real names.