Spider holes date back to World War II
, the Japanese were using them to launch ambush
es from. Most recently the word resurfaced in the news when the capture of Saddam Hussein
Spider holes are nothing elaborate, merely just a tunnel
into the ground with a vent, airhole and possibly a tube to be used as a crude urinal.
Spider holes are defined as a tight, camouflaged hiding place
hence they are not
intended for someone to be there for very long.
For those interested in a tour
of such a hole they have become commercialized in Vietnam
and there are called Cu Chi Tunnels
update:TenMinJoe says re spider hole: Chatbox consensus is that they are called spider-holes after the trapdoor spider that leaps out of holes to ambush insects.