An underwater kelp farm: a small honey-block flying machine sweeps along 240 kelp plants on the ocean floor, the kelp floats up and a water layer on the surface carries it into a chest. Over 1,000 kelp per hour.
This design works in Minecraft Java 1.16+.
Tick what you have gathered — it is remembered together with your step progress.
White Stained Glass4 stacks + 57×313Kelp3 stacks + 48×240
Water Bucket×57
Oak Sign×8
Honey Block×6
Packed Ice×4
Observer×3
Sticky Piston×3
Chest2 waterlogged (add water)×2
Obsidian×2
Spruce Trapdoor2 waterlogged (add water)×2
Hopper×1
Lever×1
Spruce Door×1
Stone×1Kelp grows on random ticks until it reaches the water surface or its maximum height; the bottom block stays when the plant is broken above it, so it regrows without replanting.
The flying machine uses honey blocks, which stick to their neighbours like slime blocks. Observers watch the sticky pistons and fire them again step by step; obsidian (which pistons cannot move) stops the machine at both ends. Pistons destroy kelp, and items float upwards in water.
The farm harvests when you flip the lever – how much you get depends on how often you do it; our tests flipped it every 5 minutes. Kelp only grows near a player (since 1.21.5 in any loaded chunk).
Water only spreads sideways over solid ground: flowing water on top of other water stays where it is. That is why the surface layer has to be made on a temporary floor.
~1,138 Kelp/h — Measured on 26.3 (Oct 15, 2026). Measured with our automated test on a local Minecraft server (fake player at the AFK spot); your rate depends on render distance, difficulty and surroundings.
This is the only version of this farm so far.
Download the original The schematic / world is offered by the creator or the tutorial author — we link to the original download.
Kelp grows by itself towards the water surface. In this farm, 6 rows of 40 kelp grow on the ocean floor. When you flip the lever at the west end, a flying machine made of honey blocks, sticky pistons and observers travels along the rows one block above the floor, breaks every kelp above its bottom block and returns.
The broken kelp floats up. On top of the ocean surface a thin layer of flowing water pushes it north into a glass channel, which carries it to a hopper and a double chest. Dry the kelp in a furnace or smoker for a great fuel (dried kelp blocks).
