A quick search of Google for "urban explorers" yields anything from a most literal underground Parisian artistic movement in some old salt mines to a guy who ventured into a defunct, cold war era missile silo. I found a flickr photoset called "Tacoma Wanderings" that has a similar flavor (thought maybe not quit the same caliber).
Flickr user samfoo and his fearless/foolish friend Scott took a little urban hike in April of '05 under 705 and up the side of the Elks. Seems like there wasn't any point other than the sport of scaling strange spots and both provided that challenge. I like the shots of them waving to cars whizzing by on 705, gazing down at a pile hypodermic caps and needles, and of them balancing Spiderman-style on the side of the Elks. Nothing completely extraordinary here but certainly a slightly different perspective than even the intrepid Tacoma Photo Gang is willing to capture.