Lime Kelp

Type	FurnitureCrafting material
Placeable	✔️ (1 wide × 2 high)
Use time	15 (Very fast)
Tooltip	Used to make Lime Dye
Rarity
Sell	20 SC
Research	3 required

The Lime Kelp is a dye material and type of plant that is found under any liquid (most commonly underwater) in the Underground and Cavern layers. It is most common in the Ice Biome, and spawns very rarely in the regular underground and cavern layers. It can only be harvested with a Pickaxe. Its sole purpose is to make Lime Dye. It can also be found in the Ocean Biome.

Lime Kelp in the water

Crafting

Used in

Result	Ingredients	Crafting station
only: Lime Dye2	Lime Kelp	Dye Vat(Desktop, Console, Old-gen console and Mobile versions)
only: Lime Dye	Lime Kelp

Notes

It is possible to find Lime Kelp in any body of water in the Dungeon and (Old-gen console and 3DS versions) also in Honey.

Tips

Lime Kelp is remarkably inconspicuous, being easy to miss even in brightly lit water. However, the Spelunker Potion or Magic Lantern will highlight them as "valuable".
Perhaps the most efficient way to "farm" Lime Kelp is to exploit the world map: After exploring in a map's underground snow biome, occasionally examine the area in the world map, zooming in to look for isolated dark green pixels in the water. (Mousing over these pixels will show "Lime Kelp" as a tooltip.) Since the world map updates with a live feed of each explored area, newly-spawned plants can be spotted by going over the map again later. This works on every biome, however kelp is more common in the Ice Biome. They are also easier to spot on the map due to the white / blue background.
Although Lime Kelp is available in placed form on the Nintendo 3DS version, breaking one never yields an item.