Tark nodded and explained from the back of the pack as we descended. "Back during the metahuman riots, we realized that we needed the means to move and support ourselves independently of contact with you Smoothies . " Tark put enough distaste into the word to let all of us know he deplored its usage. "What few people realize is that any major metropolitan area is crisscrossed with tunnels of various and sundry sizes. Sewer lines, oid subway systems that have been abandoned, and here, in Seattle, the whole Undercity, have provided us with virtual highways for unseen travel. Over the years, we have researched and reopened portions of tunnels and sewers cut off by past reconstruction projects. We have also created new entry points, much like the one we used above, to give ourselves new bolt holes if we need them."