The obstacle course was an area of the salvage yard that Chance and Jake used to keep in shape. It included piles of scrap to climb over, and a pool of oily water which they swung over. More or less, a curde version of the reflex-room. It was on the obstacle course that Jake discovered Chance couldn’t swim, when Chance’s rope broke while swinging over the pool and he fell in. Jake initially thought his buddy was pretending to drown, so as to slow him down, but he realizes Chance wasn’t fooling around in time to leap in and save him.