The tunnels were for storing canned foods and growing mushrooms?
Of course!
The Viet Cong used theirs for raising a gazillion cockroaches and spiders as big as my hand, plus infecting passing USMC tourists with lice, fleas and dysentery. For some reason they decided to use the floor of the tunnel as a latrine.
Depending on the culture, tunnels have many varied and fascinating uses. Hamas just proves this fact!
/s