-Before facing Sniper Wolf the second time, over the right side of the wall is a ration. Then go out to the blizzard. When the battle begins there will be another ration at that same location.
-When the game starts, Snake has to go under something to get to the elevator. Instead of doing so, go down the stairs, back into the water. There will be a platform with a crate. There is a ration behind the crate.