Yeah a lot of smooth surfaces and nothing to grab on to. Trusting a rope and a couple of suction cups.

There have been a few stunts on the arch over the years--some successful, others fatal.

One guy climbed all the way up the leg with suction cups and safely parachuted down.

Another guy jumped out of a plane and tried to land his parachute at the top. He almost did it, but he started sliding down the leg and his parachute collapsed. Due to the angle, his reserve wouldn't open either. Slid all the way to the bottom and died. His wife watched the whole thing. Pretty sad deal.