Seaweed is a Plant introduced in the Shipwrecked DLC. They can be found in the Shallow Ocean and in Coral Reefs. They can be harvested by the player to acquire Seaweed and will then regrow slowly. Seaweed Plants may sometimes spawn in a large group all in one place, like a real life kelp forest.
The ability to gather Seaweed Stalks and plant them elsewhere was added to the Shipwrecked DLC more than a year after its official completion in the Home Sea Home update, after being tested in a beta branch for several months.
While Seaweed Plants can grow naturally in Coral Reefs, they cannot be planted there by the player.