Don't hold your breathG 15

Not as hard as the rarity suggests. At the very end of mission 8 you’ll leave a submarine pen and reach a sniper position overlooking it. You’ll need to shoot the fuel pump (that you just sabotaged before leaving the sub pen) without using the hold breath/“empty lung” ability.

As I recall it’s a ~250 meter shot, so use left and right on the D pad to adjust your scope to the closest setting (200m for my rifle) and aim appropriately - a bit high in my case to account for the extra 50m.

If you miss, no sweat, there’s no time limit and you can take as many shots as you have bullets. You can even save the game first and reload it if you manage to run out of rifle ammo.