Water Arrows are a type of arrow and tool used for the Bow available at Garrett's disposal in Thief. The release of water from the barrel upon impact extinguishes small or medium-sized sources of flame such as torches, fireplaces or braziers. This allows the user to have an ease of access in dark areas, making it harder for nearby enemies to notice the user. It costs only 4 gold to purchase.
Listed as "DryIceArrow" in the game files.