On a long bridge, after using your Swingshot for the second time, after the second turret, go right and you will see a closed door. Look to the right of the door and you will see a ledge with a tripad on it. Jump to it and continue around the building until all three tripads are activated. Go back down and the door will be open with boxes and the gold bolt in it.
During the section where you use the Hydrodisplacer, go to the pool of water with the stairs at the right. Look down from the edge, over the railing, (top of the stairs) and you will see a large square opening below formed by four walls, on the right. Jump into the opening and you will fall down to the gold bolt.