Known in Japanese as "Uchimizu," Water Shot is simply a basic technique of Fish-Man Karate, a martial art practiced by fish-men and merfolk alike in the One Piece universe. The term literally means "water shot," which literally involves throwing an ordinary droplet of water at an enemy so powerfully and precisely that it acts like a bullet. The true power of Water Shot does not come from the quantity of water but from the user who can manipulate, compress, and use water as a projectile with the aid of Fish-Man Karate.
One shall be in a very high level of skill and control in Water Manipulation to perform a Water Shot. With this technique, users of Fish-Man Karate—as Jinbe does—former Warlord of the Sea and currently a Straw Hat Pirate—are able to scoop up any nearby water into their hands and let it fly at incredibly high velocities and great accuracy. This is highly effective for the simple reason that it is versatile, and there is lots of water lying around in the One Piece world, especially in aquatic environments where fish-men often inhabit.
Water Shot does not always need an aquatic environment. Indeed, experts can do this technique on land, simply using moisture from the air or tiny droplets of water. This is the reason why Water Shot is such a very powerful attack in various fighting conditions, unleashing Fish-Man Karate's true power.
The visual effects used by the anime to convey Water Shot are extremely striking. Usually, once it is cast, the droplet of water is rendered as a fast-moving projectile, sometimes even morphing into the likeness of a sharp, piercing arrow. This added visual effect gives an impression that puts great emphasis on the power and precision of the technique by showing how something so simple as a droplet of water can become deadly when infused with the expertise of a Fish-Man Karate practitioner.
Although Water Shot is a basic technique in Fish-Man Karate, it lays a foundation on which advanced manipulation of water-based attacks will be built. Take the case of Hody Jones, one of the antagonists of the Fish-Man Island arc; he had his own variant called "Yabusame." He would throw droplets of water in quick succession, making a hail of water bullets. Notice the full extent to which basic techniques like Water Shots can be expanded and modified by other users of Fish-Man Karate.
Worth noting is the fact that Fish-Man Karate and techniques like Water Shot are mainly used by fish-men and merfolk. However, they are not entirely exclusive to these races. Humans could also be instructed in the rudimentary Fish-Man Karate, including Water Shot. Nevertheless, some of the moves will be quite hard to perform or less effective when humans do them because they have been tailored for the fish-man physiology. What is more, this adds depth to the Fish-Man Karate martial art in the One Piece world with its unique advantages and cultural significance it holds for aquatic races.
In the case of combat, Water Shot proves that sometimes even the most basic techniques can really hold unsurpassed power if mastered. Taking something as innocuous as a droplet of water and making it into a piercing projectile shows just how creative this series really is with combat abilities and techniques. It also speaks to an important idea that runs through One Piece's conception of martial arts or other fighting styles: skill and mastery trump simple raw power.
Other media, aside from the manga and anime series, have also featured Water Shot. In "One Piece Cruise," players can throw water from their hands, which acts like a dart in a Fish-Man Karate skill known as Water Shot. The mechanics usually require its precision-based execution, much like it is depicted in its source material.