Guerrilla Exploring in North Korea isn't tricky, isn't impossible, it's just very hard with a few risks. The main risk being imprisoned for life or shot as a spy.
Soldier - "Why are you in this sewer/train tunnel/empty building?"
Soldier - "I enjoy exploring out of the way places, it's a hobby."
Soldier - "Bullshit, you spy!" Blam Blam!
Slightly exaggerated maybe, but you get the idea. This leaves few options for those of a curious nature, and those options are limited pretty much to your hotel. For pretty much every tourist in North Korea, your stay will likely be at the Yanggakdo Hotel (Seen below, the bus is the typical transport for all tours). A fine modern hotel that just happens to be on an island in the middle of the Taedong River, a guard sits at the end of the drive to the mainland to ensure your safety.

I had tried to get to the roof, helped by the fact there's a restaurant on top. However finding access was tricky, and the waitresses kept spotting me, and helpfully lead me back to the lifts. It was at the lifts that I noted there was something amiss. Can you spot it dear reader?

Indeed, for those who are numerate, there appears to be a floor missing between 4 and 6. I wondered if this was superstition or something, but apparently not. If anything the number 4 is superstitious in South Korea certainly, and is absent from lifts down there. This left an element of mystery, and also something I could investigate. I went to the 6th floor, and descended the fire stairs by the lift core. On most floors a door lead off from the stairs, however on the floor (it did exist, i think) between the 6th and 4th, it was missing. Just a curved blank wall and a vent grill.

Hmmm, this was interesting. I then searched around the 4th floor for any other stairwells. As I was searching, a stern looking chap in a dark suit came over to me. "Can I help you?" "Erm, was just looking for a way up chief." "The lifts are over there." Oh, cheers guv." I decided to go to the basement, and slam some beers with the bankers from Singapore, who spent most of the trip in the bar, even skipping some of the tour.
The next evening after another day of whizzing around North Korea, I decided to search again from the 6th floor this time. Along a corridor I found an unmarked door that opened. Looking about extremely suspiciously, I popped in. It was another stairwell that went down. This must be it I thought. And sure enough, there was the number 5 and a doorway.

There was a red closed door on the other side, I nervously pushed it open, and stood listening for a few minutes. Both to the stairwell behind me in case I'd been seen, and to the corridor on the other side of the red door. Nothing heard, I pushed the door fully open, and walked in. It was a bit like I would have expected in a basement, a number of painted pipes visible along the ceiling, and some single and double doors that were higher than normal hotel room doors. The thing that was also obvious along the walls, that differed from every other floor, were numerous murals. It was obvious this was an area for North Korean staff only.
This first mural deals with North Korea waking being willing to let it's population loose on a closed internet system (it will never access pages outside the DPRK). North Koreans will get to use computers, faxes and printers, that the West has been using for 30 years. "21st century is the age of the information industry." "Fast development of the information industry makes the national economy in all regions"

This one deals with Kim Il Sung, the red flower represents the first leader of North Korea, and eternal President. The headline is "Father General is the best!" Which is one of Kim Il Sung's many titles.

This one also deals with the 'Father General.'

These are a collection of the thoughts of Kim Jung Il and Kim Il Sung, to inspire and encourage Johnny Korean.

This one talks is an anti-Japanese mural, "Japanese Empire is the desperate enemy of the DPRK"

This one tackles everyone's favourite evil empire, the USA. "We will get vengeance on the American wolves 1100-fold." and "American empire is our enemy for 100 years." Interesting to note they say "Me-jae" instead of "Me-gook," the normal name for the US. The "jae" indicates "empire" as opposed to "nation."

It's thought this says putting the military first makes the country strong. The only flag that can somewhat be read has the word "bomb" on it.

This one is about always being ready for the threat of attack. Keeping the populace in a state of fear, a bit like in the West with terrorism. "Aggressors can surprise us any time, always be ready!" The sign says "Military demarcation line" aka the DMZ.

And with that, I buggered off. I returned with my Japanese roommate the following evening, and he translated the gist of some of them, including one that denounces Japan. The opportunities were certainly there in North Korea, not least the attractive abandoned looking fairground spotted on the way to the Revolutionary Martyrs cemetery. Although the main target, other than Kwangmyŏng disused metro station of course, the 330m white elephant that is the Ryugyong Hotel. Somehow, after misleading the ship guard as to my intentions, I whizzed up to the bird's nest of the USS Pueblo (a captured American ship). However, this was just a prank, rather than an explore. Still, finding a moment of freedom in North Korea is worth it, just for the craic!

I could also see some drain outlets, which looked like they were worthy of a nosey. 

When on the Metro, I was told off for taking a photo of the tunnel entrance. However I had taken two pictures, and deleted the one that was poorest.