Ink is the main projectile used in Splatoon and Splatoon 2 as well as a means of navigation. It comes in a variety of team-based colors that are randomized with each battle. Walls and ground alike can be covered with Ink, but it goes through grates and cannot be applied to Ink-resistant surfaces such as glass, mats, and the inflatable barriers present in some stages. It allows players a degree of stealthiness, as Inklings in squid form can hide in their own Ink and ambush enemies.
Ink can be used in a variety of ways, including as a projectile. Being hit by enemy Ink causes Inklings to take damage and become visible to their opponents on . After taking enough damage, Inklings will be splatted and eventually respawn. When attempting to swim or walk through enemy Ink, Inklings take damage, though this alone cannot splat them. Their movements also become very slow, and if they are in squid form, they will be forced back into humanoid form. Equipping gear with the Ink Resistance Up ability helps to reduce the effects of being in enemy Ink, and Defense Up reduces damage taken from being hit by it.
Ink can also be fired at various inkable surfaces. Once a surface is coated in Ink, Inkings in squid form can swim through it, allowing them to move more quickly and climb up walls. When staying still in their own Ink, Inklings in squid form can hide and ambush enemies, and when moving they will only create small ripples. Equipping gear with the Ninja Squid ability hides these ripples, further improving the wearer's ability to move undetected.
Main Weapons and Sub Weapons both require Ink, with the specific amount needed varying between different weapons. Ink requirements can be reduced by equipping the Ink Saver (Main), Ink Saver (Sub), Last-Ditch Effort, and Comeback abilities. If Inklings do not have enough Ink to use a weapon, they will be warned of it and their Ink Tank will flash with a large red "X". Ink will slowly refill automatically, but swimming one's own Ink in squid form will refill it much faster. Ink Recovery Up will increase the speed at which Ink is regained.
In Octo Valley, Ink is used in even more ways. Inkrails exist for transportation, as Inklings in squid form can use them to get to otherwise inaccessible areas. Sponge Blocks expand for use as a platform when hit by Agent 3's Ink and shrink when hit by that of an Octarian. Splat-Switches, when covered with Ink, will cause objects to move. Ink can also be used to spin Propellers, which power the movement of various platforms.
Neutral color values are used for objects such as barriers and the small dummies in the Shooting Range and can help with identifying a set. However, some sets seem to use different values for some objects.
Ink color names come from what they are called in Splatoon's files. Some names do not match the visible color; the reason for this is unknown.
Color sets used in-game include the following:[Note]
Several Ink colors and combinations, as shown in Sunken Scroll 7.
Blackbelly Skatepark coated in orange and blue Ink.
Old version of Camp Triggerfish covered in pink and teal Ink.
Octo Valley Ink
Color Locked Ink
Names in other languages