Harpoon Gun
From WikiRaider
The Harpoon has been available since Tomb Raider 2. Is is unique as it can be used underwater and above water.
It's best used only when in the water, against sharks, barracudas and divers. It's generally not that effective. If possible it's better if you climb out of the water and use the pistols. Although the Harpoon launcher can be more effective in a few circumstances. The Hydro Propeller uses the same ammo
The ammo for the harpoon guns are these simple arrows:
