The tunnels that move goods into the Gaza Strip from Egypt have been linchpins of the economy, employing 12,000 to 15,000 and supplying as much as 75 percent of the products sold in the markets, according to Sameer Abumdallala, head of the economics department at Al Azhar University in Gaza.

Pictured, Emad Shaaer has owned seven tunnels over two decades of smuggling.