South of the Danforth, in an industrial building that houses art studios, fashion labels, and commercial bakeries, I cling to fake rocks a few metres off the ground. I inch my right foot around a plastic outcropping. Then my left foot slips and I slide down the artificial rock face, skinning a couple of calluses from my hands in the process. Back on the ground, I am unable to wipe the smile off my face. The Rock Oasis is an apt name for one of the best and biggest climbing gyms in Toronto. When you push open the door, The Rock Oasis appears like a mirage: a two-story expanse of…