This week, the Israeli Defense Forces announced it was close to destroying the last tunnel in Gaza — one of Israel's stated objectives for its weeks-long offensive.

Israel has long maintained that the network of tunnels dug by Palestinian militants underneath the borders of the Gaza Strip pose a grave security threat. “It cannot be that the citizens of the state of Israel will live under the deadly threat of missiles and infiltration through tunnels,” Israeli Prime Minister Benjamin Netanyahu said last week.

On several occasions, militants have managed to kill Israeli soldiers after sneaking into Israel via the tunnels, which loom large in the public imagination. (One urban myth on social media in Israel, according to the Washington Post, is that Israeli children can hear shoveling beneath their beds.)

But what do the tunnels really look like?