how do you open all 3 hatches in lunatic pandora with laguna?

[Sir Laguna...]

I finally open the third door, I just walk on this a lot of times, Laguna will say that is impossible to open because is Stuck, later, whe you meke explode the near rock, the door open by the explosion.

[Cy]

that's the third door it's the first door i can't open

[Dazlar Bynon]

There are 2 boulders, one is used for the third hatch. Maybe that has something to do with it, I don't know how, but it may! I always find two keys, mayby you need to find a third???