How to Build a Guardian Farm at an Ocean Monument

A guardian farm is the largest project in this series and the most rewarding. Ocean monuments spawn guardians continuously in a fixed volume, which means once you control that volume you have the highest-throughput XP and item farm in the game.

Why monuments are special

Guardians spawn only in the water inside an ocean monument's bounding box, and they spawn there regardless of light level. That is unusual and enormously useful: you do not need to light-proof anything, and the spawn area is a known, fixed volume you can build around.

Drops are prismarine shards, prismarine crystals, raw cod, and a large amount of experience.

First: the Elder Guardians

A monument contains three Elder Guardians, and they inflict Mining Fatigue III on any player nearby. This effect makes breaking blocks almost impossibly slow and it will stop your build dead.

Two things to know:

• Drinking milk removes it immediately. Bring a lot of milk buckets — this is not optional equipment.
• The effect reapplies periodically while an Elder Guardian is alive and you are in range.

So the first job is always the same: hunt down and kill all three Elder Guardians before attempting any construction. They sit in the top room and in two wing rooms. Once all three are dead, the effect stops for good and the monument becomes a normal build site.

Each Elder Guardian also drops a sponge, which is directly useful for the next step.

Gear you need

• Respiration on a helmet and Aqua Affinity — these transform underwater work. Our max enchantments tool shows everything a helmet can hold.
• Depth Strider boots for movement.
• Potions of Water Breathing and Night Vision. Both are close to essential. See our brewing guide.
• Milk buckets, plural.
• Sponges for drying, from the Elder Guardians and from the sponge room.
• A door or conduit. A conduit is the ideal solution — it grants underwater breathing, night vision and faster mining in a radius, which is exactly what this build needs.

Building a conduit needs a heart of the sea and eight nautilus shells — our AFK fish farm guide covers a reliable way to collect the shells.

Two approaches

Drain the monument. Wall off the monument, remove the water with sponges, and build a dry structure inside. Enormous work, but the result is a comfortable build environment and full control.

Build in place. Leave the water, and construct collection channels that carry guardians to a kill point. Much less digging, but all the work happens underwater.

Most players do a hybrid: drain the specific volume they need for the kill chamber and collection system, and leave the rest flooded as spawning space.

The basic design

1. 1.Kill all three Elder Guardians.
2. 2.Establish the bounding box. Guardians only spawn inside the monument's defined volume, so you need to know where it ends. Building corner markers helps.
3. 3.Remove other spawn surfaces inside the box where you do not want spawns, so guardians appear in the water you control.
4. 4.Use water flow to move them toward a central point. Guardians are aquatic and are carried by currents like any other mob.
5. 5.Kill them. A drop into a dry chamber suffocates them out of water, or a long fall does the job. Finishing by hand gives you the XP.
6. 6.Hoppers into chests for the prismarine and cod.

What you get

• Experience at the best rate in the game. Enough to keep any enchanting setup permanently supplied.
• Prismarine, prismarine bricks and dark prismarine — excellent building blocks, and available in no other quantity anywhere.
• Sea lanterns, crafted from prismarine shards and crystals. The best decorative light source in the game.
• Raw cod in bulk, which is fine food and feeds cats and axolotls.

Is it worth it?

Honestly: only if you want it. This is a multi-session project involving underwater construction, and the enderman farm delivers comparable XP for a fraction of the effort.

What the guardian farm gives you that nothing else does is prismarine and sea lanterns in unlimited quantity. If you are building seriously and want those materials, or you simply want the biggest farm in your world, this is the one. If you just want levels, build the enderman farm instead and come back to this later.

Getting there safely

Ocean monuments are far from shore and deep. Bring a boat, mark the coordinates, and set up a small base on the surface above before starting. Drowned spawn in the surrounding ocean and carry tridents — our trident guide covers turning that hazard into a reward.