Where are they located ? I can't sem to find them, one should be close by when u start the mission, one is (I guess) fuether east in the underwater temple of some sort.. and the other.. well I can,t find any one of them :-() help ??
The third one leads you off to the south. One of the two buildings there has vines you can jump and grab to climb up to the ledge. Blow up that door with markings on it using any explosives you may have (C4, mines, grenades, or either launcher).
There is one in the temple underwater, it's on the floor, it can be hard to spot, you have to be really close for the ''press square message'' to pop up. The second one was in a small ruin up on a hill I think...The third one was describe correctly by the other poster. You have to blow the wall up where is the vine, then go left it's in the room in front, but you have to go around because there is a ladder blocking you.