The tunnels are hundreds of feet below the earth's surface and stretch from the North Korean side of the heavily fortified Demilitarized Zone into neighbouring South Korea.
A Melburnian who works as a North Korea tour guide has a fresh perspective on the hermit nation.
Kiwi freeskier Sam Smoothy is used to going off-piste - but when it comes to strange ski destinations, North Korea is right up there.
North Korea: how to visit the world's most secretive country
Would you risk travelling to a country where you can be imprisoned for no good reason for an unlimited amount of time?
A place so bizarre it seems almost unbelievable. And I can't wait to go there.
These are cities that are truly different. Where nothing makes sense. And travellers will love them.