I have a question about this as well. If you have 4 boulders all together in the canyon, can the heroes use awareness to get by them at all? the rules say "nearest adjacent open square" but also later say to ignore obstacles. So does that mean a hero can finish their movement on boulder? could they use 2 successful awareness checks to get by? or is their only option to use might checks at this point?
Their only option is a Might check. The "ignoring obstacles" is to signify that they won't block the path from point A (hero's origin space) to point B (empty space adjacent to said boulder), but the restriction for where he can move to still applies. It must be an empty space.
Also note that boulders are not obstacles. Obstacle is a specific term, and the objective tokens just say "they block line of sight and movement", which also happens to be what obstacles do, but anything referring to an obstacle does NOT include these boulders. For example: Any figure with FLY can ignore obstacles while moving, and they could NOT ignore the boulders.
Another hint is that all actions unless otherwise specified can not be interrupted, so you couldn't perform one Awareness check, then while floating somewhere in the middle, before being placed in an empty space, perform a second Awareness check. Each one has to be fully completed separately.